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[X86] Turn (and (shl X, C1), C2) into (shl (and X, (C1 >> C2), C2) if the AND could match a movzx. 

Could get further improvements by recognizing (i64 and (anyext (i32 shl))).

llvm-svn: 358737
This commit is contained in:
Craig Topper 2019-04-19 05:48:13 +00:00
parent 2099ccbe1f
commit bb769a2946
2 changed files with 5 additions and 4 deletions
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3
llvm/lib/Target/X86/X86ISelDAGToDAG.cpp
View File

@ -4009,6 +4009,9 @@ void X86DAGToDAGISel::Select(SDNode *Node) {
ShiftedVal = (uint64_t)Val >> ShAmt;
if (NVT == MVT::i64 && !isUInt<32>(Val) && isUInt<32>(ShiftedVal))
return true;
// Also swap order when the AND can become MOVZX.
if (ShiftedVal == UINT8_MAX || ShiftedVal == UINT16_MAX)
return true;
}
ShiftedVal = Val >> ShAmt;
if ((!isInt<8>(Val) && isInt<8>(ShiftedVal)) ||

6
llvm/test/CodeGen/X86/narrow-shl-cst.ll
View File

@ -201,9 +201,8 @@ define i64 @test16(i64 %x, i64* %y) nounwind {
define i32 @test17(i32 %x) nounwind {
; CHECK-LABEL: test17:
; CHECK: # %bb.0:
; CHECK-NEXT: movl %edi, %eax
; CHECK-NEXT: movzbl %dil, %eax
; CHECK-NEXT: shll $10, %eax
; CHECK-NEXT: andl $261120, %eax # imm = 0x3FC00
; CHECK-NEXT: retq
%and = shl i32 %x, 10
%shl = and i32 %and, 261120
@ -225,9 +224,8 @@ define i64 @test18(i64 %x) nounwind {
define i32 @test19(i32 %x) nounwind {
; CHECK-LABEL: test19:
; CHECK: # %bb.0:
; CHECK-NEXT: movl %edi, %eax
; CHECK-NEXT: movzwl %di, %eax
; CHECK-NEXT: shll $10, %eax
; CHECK-NEXT: andl $67107840, %eax # imm = 0x3FFFC00
; CHECK-NEXT: retq
%and = shl i32 %x, 10
%shl = and i32 %and, 67107840