547 lines
		
	
	
		
			25 KiB
		
	
	
	
		
			LLVM
		
	
	
	
			
		
		
	
	
			547 lines
		
	
	
		
			25 KiB
		
	
	
	
		
			LLVM
		
	
	
	
| ; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
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| ; RUN: opt -mtriple=x86_64-unknown-unknown -select-optimize -S < %s | FileCheck %s
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| 
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| ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
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| ;; Test base heuristic 1:
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| ;; highly-biased selects assumed to be highly predictable, converted to branches
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| ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
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| 
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| ; If a select is obviously predictable, turn it into a branch.
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| define i32 @weighted_select1(i32 %a, i32 %b, i1 %cmp) {
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| ; CHECK-LABEL: @weighted_select1(
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| ; CHECK-NEXT:    [[SEL_FROZEN:%.*]] = freeze i1 [[CMP:%.*]]
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| ; CHECK-NEXT:    br i1 [[SEL_FROZEN]], label [[SELECT_END:%.*]], label [[SELECT_FALSE:%.*]], !prof [[PROF16:![0-9]+]]
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| ; CHECK:       select.false:
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| ; CHECK-NEXT:    br label [[SELECT_END]]
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| ; CHECK:       select.end:
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| ; CHECK-NEXT:    [[SEL:%.*]] = phi i32 [ [[A:%.*]], [[TMP0:%.*]] ], [ [[B:%.*]], [[SELECT_FALSE]] ]
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| ; CHECK-NEXT:    ret i32 [[SEL]]
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| ;
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|   %sel = select i1 %cmp, i32 %a, i32 %b, !prof !15
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|   ret i32 %sel
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| }
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| 
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| ; If a select is obviously predictable (reversed profile weights),
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| ; turn it into a branch.
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| define i32 @weighted_select2(i32 %a, i32 %b, i1 %cmp) {
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| ; CHECK-LABEL: @weighted_select2(
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| ; CHECK-NEXT:    [[SEL_FROZEN:%.*]] = freeze i1 [[CMP:%.*]]
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| ; CHECK-NEXT:    br i1 [[SEL_FROZEN]], label [[SELECT_END:%.*]], label [[SELECT_FALSE:%.*]], !prof [[PROF17:![0-9]+]]
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| ; CHECK:       select.false:
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| ; CHECK-NEXT:    br label [[SELECT_END]]
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| ; CHECK:       select.end:
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| ; CHECK-NEXT:    [[SEL:%.*]] = phi i32 [ [[A:%.*]], [[TMP0:%.*]] ], [ [[B:%.*]], [[SELECT_FALSE]] ]
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| ; CHECK-NEXT:    ret i32 [[SEL]]
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| ;
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|   %sel = select i1 %cmp, i32 %a, i32 %b, !prof !16
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|   ret i32 %sel
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| }
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| 
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| ; Not obvioulsy predictable select.
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| define i32 @weighted_select3(i32 %a, i32 %b, i1 %cmp) {
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| ; CHECK-LABEL: @weighted_select3(
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| ; CHECK-NEXT:    [[SEL:%.*]] = select i1 [[CMP:%.*]], i32 [[A:%.*]], i32 [[B:%.*]], !prof [[PROF18:![0-9]+]]
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| ; CHECK-NEXT:    ret i32 [[SEL]]
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| ;
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|   %sel = select i1 %cmp, i32 %a, i32 %b, !prof !17
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|   ret i32 %sel
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| }
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| 
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| ; Unpredictable select should not form a branch.
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| define i32 @unpred_select(i32 %a, i32 %b, i1 %cmp) {
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| ; CHECK-LABEL: @unpred_select(
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| ; CHECK-NEXT:    [[SEL:%.*]] = select i1 [[CMP:%.*]], i32 [[A:%.*]], i32 [[B:%.*]], !unpredictable !19
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| ; CHECK-NEXT:    ret i32 [[SEL]]
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| ;
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|   %sel = select i1 %cmp, i32 %a, i32 %b, !unpredictable !20
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|   ret i32 %sel
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| }
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| 
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| ; Predictable select in function with optsize attribute should not form branch.
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| define i32 @weighted_select_optsize(i32 %a, i32 %b, i1 %cmp) optsize {
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| ; CHECK-LABEL: @weighted_select_optsize(
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| ; CHECK-NEXT:    [[SEL:%.*]] = select i1 [[CMP:%.*]], i32 [[A:%.*]], i32 [[B:%.*]], !prof [[PROF16]]
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| ; CHECK-NEXT:    ret i32 [[SEL]]
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| ;
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|   %sel = select i1 %cmp, i32 %a, i32 %b, !prof !15
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|   ret i32 %sel
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| }
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| 
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| define i32 @weighted_select_pgso(i32 %a, i32 %b, i1 %cmp) !prof !14 {
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| ; CHECK-LABEL: @weighted_select_pgso(
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| ; CHECK-NEXT:    [[SEL:%.*]] = select i1 [[CMP:%.*]], i32 [[A:%.*]], i32 [[B:%.*]], !prof [[PROF16]]
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| ; CHECK-NEXT:    ret i32 [[SEL]]
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| ;
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|   %sel = select i1 %cmp, i32 %a, i32 %b, !prof !15
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|   ret i32 %sel
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| }
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| 
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| ; If two selects in a row are predictable, turn them into branches.
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| define i32 @weighted_selects(i32 %a, i32 %b) !prof !19 {
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| ; CHECK-LABEL: @weighted_selects(
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| ; CHECK-NEXT:    [[CMP:%.*]] = icmp ne i32 [[A:%.*]], 0
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| ; CHECK-NEXT:    [[SEL_FROZEN:%.*]] = freeze i1 [[CMP]]
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| ; CHECK-NEXT:    br i1 [[SEL_FROZEN]], label [[SELECT_END:%.*]], label [[SELECT_FALSE:%.*]], !prof [[PROF16]]
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| ; CHECK:       select.false:
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| ; CHECK-NEXT:    br label [[SELECT_END]]
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| ; CHECK:       select.end:
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| ; CHECK-NEXT:    [[SEL:%.*]] = phi i32 [ [[A]], [[TMP0:%.*]] ], [ [[B:%.*]], [[SELECT_FALSE]] ]
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| ; CHECK-NEXT:    [[CMP1:%.*]] = icmp ne i32 [[SEL]], 0
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| ; CHECK-NEXT:    [[SEL1_FROZEN:%.*]] = freeze i1 [[CMP1]]
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| ; CHECK-NEXT:    br i1 [[SEL1_FROZEN]], label [[SELECT_END1:%.*]], label [[SELECT_FALSE2:%.*]], !prof [[PROF16]]
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| ; CHECK:       select.false2:
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| ; CHECK-NEXT:    br label [[SELECT_END1]]
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| ; CHECK:       select.end1:
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| ; CHECK-NEXT:    [[SEL1:%.*]] = phi i32 [ [[B]], [[SELECT_END]] ], [ [[A]], [[SELECT_FALSE2]] ]
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| ; CHECK-NEXT:    ret i32 [[SEL1]]
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| ;
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|   %cmp = icmp ne i32 %a, 0
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|   %sel = select i1 %cmp, i32 %a, i32 %b, !prof !15
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|   %cmp1 = icmp ne i32 %sel, 0
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|   %sel1 = select i1 %cmp1, i32 %b, i32 %a, !prof !15
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|   ret i32 %sel1
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| }
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| 
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| ; If select group predictable, turn it into a branch.
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| define i32 @weighted_select_group(i32 %a, i32 %b, i32 %c, i1 %cmp) !prof !19 {
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| ; CHECK-LABEL: @weighted_select_group(
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| ; CHECK-NEXT:    [[A1:%.*]] = add i32 [[A:%.*]], 1
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| ; CHECK-NEXT:    [[SEL1_FROZEN:%.*]] = freeze i1 [[CMP:%.*]]
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| ; CHECK-NEXT:    br i1 [[SEL1_FROZEN]], label [[SELECT_TRUE_SINK:%.*]], label [[SELECT_FALSE_SINK:%.*]], !prof [[PROF16]]
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| ; CHECK:       select.true.sink:
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| ; CHECK-NEXT:    [[C1:%.*]] = add i32 [[C:%.*]], 1
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| ; CHECK-NEXT:    br label [[SELECT_END:%.*]]
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| ; CHECK:       select.false.sink:
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| ; CHECK-NEXT:    [[B1:%.*]] = add i32 [[B:%.*]], 1
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| ; CHECK-NEXT:    br label [[SELECT_END]]
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| ; CHECK:       select.end:
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| ; CHECK-NEXT:    [[SEL1:%.*]] = phi i32 [ [[A1]], [[SELECT_TRUE_SINK]] ], [ [[B1]], [[SELECT_FALSE_SINK]] ]
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| ; CHECK-NEXT:    [[SEL2:%.*]] = phi i32 [ [[C1]], [[SELECT_TRUE_SINK]] ], [ [[A1]], [[SELECT_FALSE_SINK]] ]
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| ; CHECK-NEXT:    call void @llvm.dbg.value(metadata i32 [[SEL1]], metadata [[META22:![0-9]+]], metadata !DIExpression()), !dbg [[DBG26:![0-9]+]]
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| ; CHECK-NEXT:    [[ADD:%.*]] = add i32 [[SEL1]], [[SEL2]]
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| ; CHECK-NEXT:    ret i32 [[ADD]]
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| ;
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|   %a1 = add i32 %a, 1
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|   %b1 = add i32 %b, 1
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|   %c1 = add i32 %c, 1
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|   %sel1 = select i1 %cmp, i32 %a1, i32 %b1, !prof !15
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|   call void @llvm.dbg.value(metadata i32 %sel1, metadata !24, metadata !DIExpression()), !dbg !DILocation(scope: !23)
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|   %sel2 = select i1 %cmp, i32 %c1, i32 %a1, !prof !15
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|   %add = add i32 %sel1, %sel2
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|   ret i32 %add
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| }
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| 
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| ; Predictable select group with intra-group dependence converted to branch
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| define i32 @select_group_intra_group(i32 %a, i32 %b, i32 %c, i1 %cmp) {
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| ; CHECK-LABEL: @select_group_intra_group(
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| ; CHECK-NEXT:    [[SEL1_FROZEN:%.*]] = freeze i1 [[CMP:%.*]]
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| ; CHECK-NEXT:    br i1 [[SEL1_FROZEN]], label [[SELECT_END:%.*]], label [[SELECT_FALSE:%.*]], !prof [[PROF16]]
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| ; CHECK:       select.false:
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| ; CHECK-NEXT:    br label [[SELECT_END]]
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| ; CHECK:       select.end:
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| ; CHECK-NEXT:    [[SEL1:%.*]] = phi i32 [ [[A:%.*]], [[TMP0:%.*]] ], [ [[B:%.*]], [[SELECT_FALSE]] ]
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| ; CHECK-NEXT:    [[SEL2:%.*]] = phi i32 [ [[C:%.*]], [[TMP0]] ], [ [[B]], [[SELECT_FALSE]] ]
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| ; CHECK-NEXT:    [[SUB:%.*]] = sub i32 [[SEL1]], [[SEL2]]
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| ; CHECK-NEXT:    ret i32 [[SUB]]
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| ;
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|   %sel1 = select i1 %cmp, i32 %a, i32 %b,!prof !15
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|   %sel2 = select i1 %cmp, i32 %c, i32 %sel1, !prof !15
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|   %sub = sub i32 %sel1, %sel2
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|   ret i32 %sub
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| }
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| 
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| ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
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| ;; Test base heuristic 2:
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| ;; look for expensive instructions in the one-use slice of the cold path
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| ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
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| 
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| ; Select with cold one-use load value operand should form branch and
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| ; sink load
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| define i32 @expensive_val_operand1(i32* nocapture %a, i32 %y, i1 %cmp) {
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| ; CHECK-LABEL: @expensive_val_operand1(
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| ; CHECK-NEXT:    [[SEL_FROZEN:%.*]] = freeze i1 [[CMP:%.*]]
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| ; CHECK-NEXT:    br i1 [[SEL_FROZEN]], label [[SELECT_TRUE_SINK:%.*]], label [[SELECT_END:%.*]], !prof [[PROF18]]
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| ; CHECK:       select.true.sink:
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| ; CHECK-NEXT:    [[LOAD:%.*]] = load i32, i32* [[A:%.*]], align 8
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| ; CHECK-NEXT:    br label [[SELECT_END]]
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| ; CHECK:       select.end:
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| ; CHECK-NEXT:    [[SEL:%.*]] = phi i32 [ [[LOAD]], [[SELECT_TRUE_SINK]] ], [ [[Y:%.*]], [[TMP0:%.*]] ]
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| ; CHECK-NEXT:    ret i32 [[SEL]]
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| ;
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|   %load = load i32, i32* %a, align 8
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|   %sel = select i1 %cmp, i32 %load, i32 %y, !prof !17
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|   ret i32 %sel
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| }
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| 
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| ; Expensive hot value operand and cheap cold value operand.
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| define i32 @expensive_val_operand2(i32* nocapture %a, i32 %x, i1 %cmp) {
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| ; CHECK-LABEL: @expensive_val_operand2(
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| ; CHECK-NEXT:    [[LOAD:%.*]] = load i32, i32* [[A:%.*]], align 8
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| ; CHECK-NEXT:    [[SEL:%.*]] = select i1 [[CMP:%.*]], i32 [[X:%.*]], i32 [[LOAD]], !prof [[PROF18]]
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| ; CHECK-NEXT:    ret i32 [[SEL]]
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| ;
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|   %load = load i32, i32* %a, align 8
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|   %sel = select i1 %cmp, i32 %x, i32 %load, !prof !17
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|   ret i32 %sel
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| }
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| 
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| ; Cold value operand with load in its one-use dependence slice shoud result
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| ; into a branch with sinked dependence slice.
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| define i32 @expensive_val_operand3(i32* nocapture %a, i32 %b, i32 %y, i1 %cmp) {
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| ; CHECK-LABEL: @expensive_val_operand3(
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| ; CHECK-NEXT:    [[SEL_FROZEN:%.*]] = freeze i1 [[CMP:%.*]]
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| ; CHECK-NEXT:    br i1 [[SEL_FROZEN]], label [[SELECT_TRUE_SINK:%.*]], label [[SELECT_END:%.*]], !prof [[PROF18]]
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| ; CHECK:       select.true.sink:
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| ; CHECK-NEXT:    [[LOAD:%.*]] = load i32, i32* [[A:%.*]], align 8
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| ; CHECK-NEXT:    [[X:%.*]] = add i32 [[LOAD]], [[B:%.*]]
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| ; CHECK-NEXT:    br label [[SELECT_END]]
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| ; CHECK:       select.end:
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| ; CHECK-NEXT:    [[SEL:%.*]] = phi i32 [ [[X]], [[SELECT_TRUE_SINK]] ], [ [[Y:%.*]], [[TMP0:%.*]] ]
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| ; CHECK-NEXT:    ret i32 [[SEL]]
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| ;
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|   %load = load i32, i32* %a, align 8
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|   %x = add i32 %load, %b
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|   %sel = select i1 %cmp, i32 %x, i32 %y, !prof !17
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|   ret i32 %sel
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| }
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| 
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| ; Multiple uses of the load value operand.
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| define i32 @expensive_val_operand4(i32 %a, i32* nocapture %b, i32 %x, i1 %cmp) {
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| ; CHECK-LABEL: @expensive_val_operand4(
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| ; CHECK-NEXT:    [[LOAD:%.*]] = load i32, i32* [[B:%.*]], align 4
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| ; CHECK-NEXT:    [[SEL:%.*]] = select i1 [[CMP:%.*]], i32 [[X:%.*]], i32 [[LOAD]]
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| ; CHECK-NEXT:    [[ADD:%.*]] = add i32 [[SEL]], [[LOAD]]
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| ; CHECK-NEXT:    ret i32 [[ADD]]
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| ;
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|   %load = load i32, i32* %b, align 4
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|   %sel = select i1 %cmp, i32 %x, i32 %load
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|   %add = add i32 %sel, %load
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|   ret i32 %add
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| }
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| 
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| ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
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| ;; Test loop heuristic: loop-level critical-path analysis
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| ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
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| 
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| ;; Use of cmov in this test would put a load and a fsub on the critical path.
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| ;; Loop-level analysis should decide to form a branch.
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| ;;
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| ;;double cmov_on_critical_path(int n, double x, double *a) {
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| ;;  for (int i = 0; i < n; i++) {
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| ;;    double r = a[i];
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| ;;    if (x > r)
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| ;; 			// 50% of iterations
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| ;;   		x -= r;
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| ;;  }
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| ;;  return x;
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| ;;}
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| define double @cmov_on_critical_path(i32 %n, double %x, double* nocapture %a) {
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| ; CHECK-LABEL: @cmov_on_critical_path(
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| ; CHECK-NEXT:  entry:
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| ; CHECK-NEXT:    [[CMP1:%.*]] = icmp sgt i32 [[N:%.*]], 0
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| ; CHECK-NEXT:    br i1 [[CMP1]], label [[FOR_BODY_PREHEADER:%.*]], label [[FOR_COND_CLEANUP:%.*]]
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| ; CHECK:       for.cond.cleanup:
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| ; CHECK-NEXT:    ret double [[X:%.*]]
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| ; CHECK:       for.body.preheader:
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| ; CHECK-NEXT:    [[WIDE_TRIP_COUNT:%.*]] = zext i32 [[N]] to i64
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| ; CHECK-NEXT:    br label [[FOR_BODY:%.*]]
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| ; CHECK:       for.body:
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| ; CHECK-NEXT:    [[INDVARS_IV:%.*]] = phi i64 [ [[INDVARS_IV_NEXT:%.*]], [[SELECT_END:%.*]] ], [ 0, [[FOR_BODY_PREHEADER]] ]
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| ; CHECK-NEXT:    [[X1:%.*]] = phi double [ [[X2:%.*]], [[SELECT_END]] ], [ [[X]], [[FOR_BODY_PREHEADER]] ]
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| ; CHECK-NEXT:    [[ARRAYIDX:%.*]] = getelementptr inbounds double, double* [[A:%.*]], i64 [[INDVARS_IV]]
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| ; CHECK-NEXT:    [[R:%.*]] = load double, double* [[ARRAYIDX]], align 8
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| ; CHECK-NEXT:    [[CMP2:%.*]] = fcmp ogt double [[X1]], [[R]]
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| ; CHECK-NEXT:    [[X2_FROZEN:%.*]] = freeze i1 [[CMP2]]
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| ; CHECK-NEXT:    br i1 [[X2_FROZEN]], label [[SELECT_TRUE_SINK:%.*]], label [[SELECT_END]], !prof [[PROF27:![0-9]+]]
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| ; CHECK:       select.true.sink:
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| ; CHECK-NEXT:    [[SUB:%.*]] = fsub double [[X1]], [[R]]
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| ; CHECK-NEXT:    br label [[SELECT_END]]
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| ; CHECK:       select.end:
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| ; CHECK-NEXT:    [[X2]] = phi double [ [[SUB]], [[SELECT_TRUE_SINK]] ], [ [[X1]], [[FOR_BODY]] ]
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| ; CHECK-NEXT:    [[INDVARS_IV_NEXT]] = add nuw nsw i64 [[INDVARS_IV]], 1
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| ; CHECK-NEXT:    [[EXITCOND:%.*]] = icmp eq i64 [[INDVARS_IV_NEXT]], [[WIDE_TRIP_COUNT]]
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| ; CHECK-NEXT:    br i1 [[EXITCOND]], label [[FOR_EXIT:%.*]], label [[FOR_BODY]]
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| ; CHECK:       for.exit:
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| ; CHECK-NEXT:    ret double [[X2]]
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| ;
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| entry:
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|   %cmp1 = icmp sgt i32 %n, 0
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|   br i1 %cmp1, label %for.body.preheader, label %for.cond.cleanup
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| 
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| for.cond.cleanup:                                 ; preds = %entry
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|   ret double %x
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| 
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| for.body.preheader:                               ; preds = %entry
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|   %wide.trip.count = zext i32 %n to i64
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|   br label %for.body
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| 
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| for.body:                                         ; preds = %for.body.preheader, %for.body
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|   %indvars.iv = phi i64 [ %indvars.iv.next, %for.body ], [ 0, %for.body.preheader ]
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|   %x1 = phi double [ %x2, %for.body ], [ %x, %for.body.preheader ]
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|   %arrayidx = getelementptr inbounds double, double* %a, i64 %indvars.iv
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|   %r = load double, double* %arrayidx, align 8
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|   %sub = fsub double %x1, %r
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|   %cmp2 = fcmp ogt double %x1, %r
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|   %x2 = select i1 %cmp2, double %sub, double %x1, !prof !18
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|   %indvars.iv.next = add nuw nsw i64 %indvars.iv, 1
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|   %exitcond = icmp eq i64 %indvars.iv.next, %wide.trip.count
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|   br i1 %exitcond, label %for.exit, label %for.body
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| 
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| for.exit:                                         ; preds = %for.body
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|   ret double %x2
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| }
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| 
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| ;; The common path includes expensive operations (load and fsub) making
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| ;; branch similarly expensive to cmov, and thus the gain is small.
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| ;; Loop-level analysis should decide on not forming a branch.
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| ;;
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| ;;double small_gain(int n, double x, double *a) {
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| ;;  for (int i = 0; i < n; i++) {
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| ;;    double r = a[i];
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| ;;    if (x > r)
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| ;;      // 99% of iterations
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| ;;      x -= r;
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| ;;  }
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| ;;  return x;
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| ;;}
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| define double @small_gain(i32 %n, double %x, double* nocapture %a) {
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| ; CHECK-LABEL: @small_gain(
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| ; CHECK-NEXT:  entry:
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| ; CHECK-NEXT:    [[CMP1:%.*]] = icmp sgt i32 [[N:%.*]], 0
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| ; CHECK-NEXT:    br i1 [[CMP1]], label [[FOR_BODY_PREHEADER:%.*]], label [[FOR_COND_CLEANUP:%.*]]
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| ; CHECK:       for.cond.cleanup:
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| ; CHECK-NEXT:    ret double [[X:%.*]]
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| ; CHECK:       for.body.preheader:
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| ; CHECK-NEXT:    [[WIDE_TRIP_COUNT:%.*]] = zext i32 [[N]] to i64
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| ; CHECK-NEXT:    br label [[FOR_BODY:%.*]]
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| ; CHECK:       for.body:
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| ; CHECK-NEXT:    [[INDVARS_IV:%.*]] = phi i64 [ [[INDVARS_IV_NEXT:%.*]], [[FOR_BODY]] ], [ 0, [[FOR_BODY_PREHEADER]] ]
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| ; CHECK-NEXT:    [[X1:%.*]] = phi double [ [[X2:%.*]], [[FOR_BODY]] ], [ [[X]], [[FOR_BODY_PREHEADER]] ]
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| ; CHECK-NEXT:    [[ARRAYIDX:%.*]] = getelementptr inbounds double, double* [[A:%.*]], i64 [[INDVARS_IV]]
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| ; CHECK-NEXT:    [[R:%.*]] = load double, double* [[ARRAYIDX]], align 8
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| ; CHECK-NEXT:    [[SUB:%.*]] = fsub double [[X1]], [[R]]
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| ; CHECK-NEXT:    [[CMP2:%.*]] = fcmp ole double [[X1]], [[R]]
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| ; CHECK-NEXT:    [[X2]] = select i1 [[CMP2]], double [[X1]], double [[SUB]], !prof [[PROF18]]
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| ; CHECK-NEXT:    [[INDVARS_IV_NEXT]] = add nuw nsw i64 [[INDVARS_IV]], 1
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| ; CHECK-NEXT:    [[EXITCOND:%.*]] = icmp eq i64 [[INDVARS_IV_NEXT]], [[WIDE_TRIP_COUNT]]
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| ; CHECK-NEXT:    br i1 [[EXITCOND]], label [[FOR_EXIT:%.*]], label [[FOR_BODY]]
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| ; CHECK:       for.exit:
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| ; CHECK-NEXT:    ret double [[X2]]
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| ;
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| entry:
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|   %cmp1 = icmp sgt i32 %n, 0
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|   br i1 %cmp1, label %for.body.preheader, label %for.cond.cleanup
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| 
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| for.cond.cleanup:                                 ; preds = %entry
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|   ret double %x
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| 
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| for.body.preheader:                               ; preds = %entry
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|   %wide.trip.count = zext i32 %n to i64
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|   br label %for.body
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| 
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| for.body:                                         ; preds = %for.body.preheader, %for.body
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|   %indvars.iv = phi i64 [ %indvars.iv.next, %for.body ], [ 0, %for.body.preheader ]
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|   %x1 = phi double [ %x2, %for.body ], [ %x, %for.body.preheader ]
 | |
|   %arrayidx = getelementptr inbounds double, double* %a, i64 %indvars.iv
 | |
|   %r = load double, double* %arrayidx, align 8
 | |
|   %sub = fsub double %x1, %r
 | |
|   %cmp2 = fcmp ole double %x1, %r
 | |
|   %x2 = select i1 %cmp2, double %x1, double %sub, !prof !17
 | |
|   %indvars.iv.next = add nuw nsw i64 %indvars.iv, 1
 | |
|   %exitcond = icmp eq i64 %indvars.iv.next, %wide.trip.count
 | |
|   br i1 %exitcond, label %for.exit, label %for.body
 | |
| 
 | |
| for.exit:                                         ; preds = %for.body
 | |
|   ret double %x2
 | |
| }
 | |
| 
 | |
| ;; Use of a branch in this test would avoid executing a load and several
 | |
| ;; floating-point operations for most cases (70% of the time).
 | |
| ;; Yet, the gain is not increasing much per iteration (small gradient gain).
 | |
| ;; Loop-level analysis should decide not to form a branch.
 | |
| ;;
 | |
| ;;double small_gradient(int n, double x, double *a) {
 | |
| ;;  for (int i = 0; i < n; i++) {
 | |
| ;;    double r = 2 * a[i] + i;
 | |
| ;;    if (r > 0)
 | |
| ;;      // 30% of iterations
 | |
| ;;      x -= r;
 | |
| ;;  }
 | |
| ;;  return x;
 | |
| ;;}
 | |
| define double @small_gradient(i32 %n, double %x, double* nocapture %a) {
 | |
| ; CHECK-LABEL: @small_gradient(
 | |
| ; CHECK-NEXT:  entry:
 | |
| ; CHECK-NEXT:    [[CMP8:%.*]] = icmp sgt i32 [[N:%.*]], 0
 | |
| ; CHECK-NEXT:    br i1 [[CMP8]], label [[FOR_BODY_PREHEADER:%.*]], label [[FOR_COND_CLEANUP:%.*]]
 | |
| ; CHECK:       for.body.preheader:
 | |
| ; CHECK-NEXT:    [[WIDE_TRIP_COUNT:%.*]] = zext i32 [[N]] to i64
 | |
| ; CHECK-NEXT:    br label [[FOR_BODY:%.*]]
 | |
| ; CHECK:       for.cond.cleanup:
 | |
| ; CHECK-NEXT:    [[X_ADDR_0_LCSSA:%.*]] = phi double [ [[X:%.*]], [[ENTRY:%.*]] ], [ [[X_ADDR_1:%.*]], [[FOR_BODY]] ]
 | |
| ; CHECK-NEXT:    ret double [[X_ADDR_0_LCSSA]]
 | |
| ; CHECK:       for.body:
 | |
| ; CHECK-NEXT:    [[INDVARS_IV:%.*]] = phi i64 [ 0, [[FOR_BODY_PREHEADER]] ], [ [[INDVARS_IV_NEXT:%.*]], [[FOR_BODY]] ]
 | |
| ; CHECK-NEXT:    [[X_ADDR_010:%.*]] = phi double [ [[X]], [[FOR_BODY_PREHEADER]] ], [ [[X_ADDR_1]], [[FOR_BODY]] ]
 | |
| ; CHECK-NEXT:    [[ARRAYIDX:%.*]] = getelementptr inbounds double, double* [[A:%.*]], i64 [[INDVARS_IV]]
 | |
| ; CHECK-NEXT:    [[TMP0:%.*]] = load double, double* [[ARRAYIDX]], align 8
 | |
| ; CHECK-NEXT:    [[TMP1:%.*]] = call double @llvm.fmuladd.f64(double [[TMP0]], double 2.000000e+00, double 1.000000e+00)
 | |
| ; CHECK-NEXT:    [[CMP1:%.*]] = fcmp ogt double [[TMP1]], 0.000000e+00
 | |
| ; CHECK-NEXT:    [[SUB:%.*]] = select i1 [[CMP1]], double [[TMP1]], double 0.000000e+00, !prof [[PROF28:![0-9]+]]
 | |
| ; CHECK-NEXT:    [[X_ADDR_1]] = fsub double [[X_ADDR_010]], [[SUB]]
 | |
| ; CHECK-NEXT:    [[INDVARS_IV_NEXT]] = add nuw nsw i64 [[INDVARS_IV]], 1
 | |
| ; CHECK-NEXT:    [[EXITCOND_NOT:%.*]] = icmp eq i64 [[INDVARS_IV_NEXT]], [[WIDE_TRIP_COUNT]]
 | |
| ; CHECK-NEXT:    br i1 [[EXITCOND_NOT]], label [[FOR_COND_CLEANUP]], label [[FOR_BODY]]
 | |
| ;
 | |
| entry:
 | |
|   %cmp8 = icmp sgt i32 %n, 0
 | |
|   br i1 %cmp8, label %for.body.preheader, label %for.cond.cleanup
 | |
| 
 | |
| for.body.preheader:                               ; preds = %entry
 | |
|   %wide.trip.count = zext i32 %n to i64
 | |
|   br label %for.body
 | |
| 
 | |
| for.cond.cleanup:                                 ; preds = %for.body, %entry
 | |
|   %x.addr.0.lcssa = phi double [ %x, %entry ], [ %x.addr.1, %for.body ]
 | |
|   ret double %x.addr.0.lcssa
 | |
| 
 | |
| for.body:                                         ; preds = %for.body.preheader, %for.body
 | |
|   %indvars.iv = phi i64 [ 0, %for.body.preheader ], [ %indvars.iv.next, %for.body ]
 | |
|   %x.addr.010 = phi double [ %x, %for.body.preheader ], [ %x.addr.1, %for.body ]
 | |
|   %arrayidx = getelementptr inbounds double, double* %a, i64 %indvars.iv
 | |
|   %0 = load double, double* %arrayidx, align 8
 | |
|   %1 = call double @llvm.fmuladd.f64(double %0, double 2.000000e+00, double 1.000000e+00)
 | |
|   %cmp1 = fcmp ogt double %1, 0.000000e+00
 | |
|   %sub = select i1 %cmp1, double %1, double 0.000000e+00, !prof !28
 | |
|   %x.addr.1 = fsub double %x.addr.010, %sub
 | |
|   %indvars.iv.next = add nuw nsw i64 %indvars.iv, 1
 | |
|   %exitcond.not = icmp eq i64 %indvars.iv.next, %wide.trip.count
 | |
|   br i1 %exitcond.not, label %for.cond.cleanup, label %for.body
 | |
| }
 | |
| 
 | |
| ;; One select on the critical path and one off the critical path.
 | |
| ;; Loop-level analysis should decide to form a branch only for
 | |
| ;; the select on the critical path.
 | |
| ;;
 | |
| ;;double loop_select_groups(int n, double x, double *a, int k) {
 | |
| ;;  int c = 0;
 | |
| ;;  for (int i = 0; i < n; i++) {
 | |
| ;;    double r = a[i];
 | |
| ;;    if (x > r)
 | |
| ;;      x -= r;
 | |
| ;;    if (i == k)
 | |
| ;;      c += n;
 | |
| ;;  }
 | |
| ;;  return x + c;
 | |
| ;;}
 | |
| define double @loop_select_groups(i32 %n, double %x, double* nocapture %a, i32 %k) {
 | |
| ; CHECK-LABEL: @loop_select_groups(
 | |
| ; CHECK-NEXT:  entry:
 | |
| ; CHECK-NEXT:    [[CMP19:%.*]] = icmp sgt i32 [[N:%.*]], 0
 | |
| ; CHECK-NEXT:    br i1 [[CMP19]], label [[FOR_BODY_PREHEADER:%.*]], label [[FOR_COND_CLEANUP:%.*]]
 | |
| ; CHECK:       for.body.preheader:
 | |
| ; CHECK-NEXT:    [[WIDE_TRIP_COUNT:%.*]] = zext i32 [[N]] to i64
 | |
| ; CHECK-NEXT:    br label [[FOR_BODY:%.*]]
 | |
| ; CHECK:       for.cond.cleanup.loopexit:
 | |
| ; CHECK-NEXT:    [[PHI_CAST:%.*]] = sitofp i32 [[C_1:%.*]] to double
 | |
| ; CHECK-NEXT:    br label [[FOR_COND_CLEANUP]]
 | |
| ; CHECK:       for.cond.cleanup:
 | |
| ; CHECK-NEXT:    [[C_0_LCSSA:%.*]] = phi double [ 0.000000e+00, [[ENTRY:%.*]] ], [ [[PHI_CAST]], [[FOR_COND_CLEANUP_LOOPEXIT:%.*]] ]
 | |
| ; CHECK-NEXT:    [[X_ADDR_0_LCSSA:%.*]] = phi double [ [[X:%.*]], [[ENTRY]] ], [ [[X_ADDR_1:%.*]], [[FOR_COND_CLEANUP_LOOPEXIT]] ]
 | |
| ; CHECK-NEXT:    [[ADD5:%.*]] = fadd double [[X_ADDR_0_LCSSA]], [[C_0_LCSSA]]
 | |
| ; CHECK-NEXT:    ret double [[ADD5]]
 | |
| ; CHECK:       for.body:
 | |
| ; CHECK-NEXT:    [[INDVARS_IV:%.*]] = phi i64 [ 0, [[FOR_BODY_PREHEADER]] ], [ [[INDVARS_IV_NEXT:%.*]], [[SELECT_END:%.*]] ]
 | |
| ; CHECK-NEXT:    [[X_ADDR_022:%.*]] = phi double [ [[X]], [[FOR_BODY_PREHEADER]] ], [ [[X_ADDR_1]], [[SELECT_END]] ]
 | |
| ; CHECK-NEXT:    [[C_020:%.*]] = phi i32 [ 0, [[FOR_BODY_PREHEADER]] ], [ [[C_1]], [[SELECT_END]] ]
 | |
| ; CHECK-NEXT:    [[ARRAYIDX:%.*]] = getelementptr inbounds double, double* [[A:%.*]], i64 [[INDVARS_IV]]
 | |
| ; CHECK-NEXT:    [[TMP0:%.*]] = load double, double* [[ARRAYIDX]], align 8
 | |
| ; CHECK-NEXT:    [[CMP1:%.*]] = fcmp ogt double [[X_ADDR_022]], [[TMP0]]
 | |
| ; CHECK-NEXT:    [[SUB_FROZEN:%.*]] = freeze i1 [[CMP1]]
 | |
| ; CHECK-NEXT:    br i1 [[SUB_FROZEN]], label [[SELECT_END]], label [[SELECT_FALSE:%.*]]
 | |
| ; CHECK:       select.false:
 | |
| ; CHECK-NEXT:    br label [[SELECT_END]]
 | |
| ; CHECK:       select.end:
 | |
| ; CHECK-NEXT:    [[SUB:%.*]] = phi double [ [[TMP0]], [[FOR_BODY]] ], [ 0.000000e+00, [[SELECT_FALSE]] ]
 | |
| ; CHECK-NEXT:    [[X_ADDR_1]] = fsub double [[X_ADDR_022]], [[SUB]]
 | |
| ; CHECK-NEXT:    [[TMP1:%.*]] = trunc i64 [[INDVARS_IV]] to i32
 | |
| ; CHECK-NEXT:    [[CMP2:%.*]] = icmp eq i32 [[K:%.*]], [[N]]
 | |
| ; CHECK-NEXT:    [[ADD:%.*]] = select i1 [[CMP2]], i32 [[N]], i32 0
 | |
| ; CHECK-NEXT:    [[C_1]] = add nsw i32 [[ADD]], [[C_020]]
 | |
| ; CHECK-NEXT:    [[INDVARS_IV_NEXT]] = add nuw nsw i64 [[INDVARS_IV]], 1
 | |
| ; CHECK-NEXT:    [[EXITCOND_NOT:%.*]] = icmp eq i64 [[INDVARS_IV_NEXT]], [[WIDE_TRIP_COUNT]]
 | |
| ; CHECK-NEXT:    br i1 [[EXITCOND_NOT]], label [[FOR_COND_CLEANUP_LOOPEXIT]], label [[FOR_BODY]]
 | |
| ;
 | |
| entry:
 | |
|   %cmp19 = icmp sgt i32 %n, 0
 | |
|   br i1 %cmp19, label %for.body.preheader, label %for.cond.cleanup
 | |
| 
 | |
| for.body.preheader:                               ; preds = %entry
 | |
|   %wide.trip.count = zext i32 %n to i64
 | |
|   br label %for.body
 | |
| 
 | |
| for.cond.cleanup.loopexit:                        ; preds = %for.body
 | |
|   %phi.cast = sitofp i32 %c.1 to double
 | |
|   br label %for.cond.cleanup
 | |
| 
 | |
| for.cond.cleanup:                                 ; preds = %for.cond.cleanup.loopexit, %entry
 | |
|   %c.0.lcssa = phi double [ 0.000000e+00, %entry ], [ %phi.cast, %for.cond.cleanup.loopexit ]
 | |
|   %x.addr.0.lcssa = phi double [ %x, %entry ], [ %x.addr.1, %for.cond.cleanup.loopexit ]
 | |
|   %add5 = fadd double %x.addr.0.lcssa, %c.0.lcssa
 | |
|   ret double %add5
 | |
| 
 | |
| for.body:                                         ; preds = %for.body.preheader, %for.body
 | |
|   %indvars.iv = phi i64 [ 0, %for.body.preheader ], [ %indvars.iv.next, %for.body ]
 | |
|   %x.addr.022 = phi double [ %x, %for.body.preheader ], [ %x.addr.1, %for.body ]
 | |
|   %c.020 = phi i32 [ 0, %for.body.preheader ], [ %c.1, %for.body ]
 | |
|   %arrayidx = getelementptr inbounds double, double* %a, i64 %indvars.iv
 | |
|   %0 = load double, double* %arrayidx, align 8
 | |
|   %cmp1 = fcmp ogt double %x.addr.022, %0
 | |
|   %sub = select i1 %cmp1, double %0, double 0.000000e+00
 | |
|   %x.addr.1 = fsub double %x.addr.022, %sub
 | |
|   %1 = trunc i64 %indvars.iv to i32
 | |
|   %cmp2 = icmp eq i32 %k, %n
 | |
|   %add = select i1 %cmp2, i32 %n, i32 0
 | |
|   %c.1 = add nsw i32 %add, %c.020
 | |
|   %indvars.iv.next = add nuw nsw i64 %indvars.iv, 1
 | |
|   %exitcond.not = icmp eq i64 %indvars.iv.next, %wide.trip.count
 | |
|   br i1 %exitcond.not, label %for.cond.cleanup.loopexit, label %for.body
 | |
| }
 | |
| 
 | |
| ; Function Attrs: nounwind readnone speculatable willreturn
 | |
| declare void @llvm.dbg.value(metadata, metadata, metadata)
 | |
| 
 | |
| ; Function Attrs: mustprogress nofree nosync nounwind readnone speculatable willreturn
 | |
| declare double @llvm.fmuladd.f64(double, double, double)
 | |
| 
 | |
| !llvm.module.flags = !{!0, !26, !27}
 | |
| !0 = !{i32 1, !"ProfileSummary", !1}
 | |
| !1 = !{!2, !3, !4, !5, !6, !7, !8, !9}
 | |
| !2 = !{!"ProfileFormat", !"InstrProf"}
 | |
| !3 = !{!"TotalCount", i64 10000}
 | |
| !4 = !{!"MaxCount", i64 10}
 | |
| !5 = !{!"MaxInternalCount", i64 1}
 | |
| !6 = !{!"MaxFunctionCount", i64 1000}
 | |
| !7 = !{!"NumCounts", i64 3}
 | |
| !8 = !{!"NumFunctions", i64 3}
 | |
| !9 = !{!"DetailedSummary", !10}
 | |
| !10 = !{!11, !12, !13}
 | |
| !11 = !{i32 10000, i64 100, i32 1}
 | |
| !12 = !{i32 999000, i64 100, i32 1}
 | |
| !13 = !{i32 999999, i64 1, i32 2}
 | |
| !14 = !{!"function_entry_count", i64 0}
 | |
| !15 = !{!"branch_weights", i32 1, i32 100}
 | |
| !16 = !{!"branch_weights", i32 100, i32 1}
 | |
| !17 = !{!"branch_weights", i32 1, i32 99}
 | |
| !18 = !{!"branch_weights", i32 50, i32 50}
 | |
| !19 = !{!"function_entry_count", i64 100}
 | |
| !20 = !{}
 | |
| !21 = !DIFile(filename: "test.c", directory: "/test")
 | |
| !22 = distinct !DICompileUnit(language: DW_LANG_C99, file: !21, producer: "clang version 15.0.0", isOptimized: true, emissionKind: FullDebug, globals: !25, splitDebugInlining: false, nameTableKind: None)
 | |
| !23 = distinct !DISubprogram(name: "test", scope: !21, file: !21, line: 1, unit: !22)
 | |
| !24 = !DILocalVariable(name: "x", scope: !23)
 | |
| !25 = !{}
 | |
| !26 = !{i32 2, !"Dwarf Version", i32 4}
 | |
| !27 = !{i32 1, !"Debug Info Version", i32 3}
 | |
| !28 = !{!"branch_weights", i32 30, i32 70}
 |