OSchip
/
llvm-project
mirror of https://github.com/THU-DSP-LAB/llvm-project.git
13
0
Fork 6
Code Issues Packages Projects Releases Wiki Activity

[AArch64][GlobalISel] Fold selects fed by G_PTR_ADD 

Similar to the case for G_ADD.

There was a function in CTMark/pairlocalalign which was missing this case,
causing GlobalISel to emit a add + csel when a csinc is all that is necessary.

https://godbolt.org/z/ax69E9

Minor code size improvements on CTMark at -Os.

Differential Revision: https://reviews.llvm.org/D96390
This commit is contained in:
Jessica Paquette 2021-02-09 18:04:44 -08:00
parent ddb01010b2
commit 7eee858585
2 changed files with 34 additions and 1 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

4
llvm/lib/Target/AArch64/GISel/AArch64InstructionSelector.cpp
View File

@ -1085,7 +1085,9 @@ AArch64InstructionSelector::emitSelect(Register Dst, Register True,
//
// Into:
// %select = CSINC %reg, %x, cc
if (mi_match(Reg, MRI, m_GAdd(m_Reg(MatchReg), m_SpecificICst(1)))) {
if (mi_match(Reg, MRI,
m_any_of(m_GAdd(m_Reg(MatchReg), m_SpecificICst(1)),
m_GPtrAdd(m_Reg(MatchReg), m_SpecificICst(1))))) {
Opc = Is32Bit ? AArch64::CSINCWr : AArch64::CSINCXr;
Reg = MatchReg;
if (Invert) {

31
llvm/test/CodeGen/AArch64/GlobalISel/select-select.mir
View File

@ -651,6 +651,37 @@ body: |
$w0 = COPY %select(s32)
RET_ReallyLR implicit $w0
...
---
name: csinc_ptr_add
legalized: true
regBankSelected: true
tracksRegLiveness: true
body: |
bb.0:
liveins: $x0, $x1, $x2
; G_SELECT cc, %true, (G_PTR_ADD %x, 1) -> CSINC %true, %x, cc
; CHECK-LABEL: name: csinc_ptr_add
; CHECK: liveins: $x0, $x1, $x2
; CHECK: %reg0:gpr64 = COPY $x0
; CHECK: %reg1:gpr64 = COPY $x1
; CHECK: %cond:gpr32 = COPY %reg0.sub_32
; CHECK: %t:gpr64 = COPY $x2
; CHECK: [[ANDSWri:%[0-9]+]]:gpr32 = ANDSWri %cond, 0, implicit-def $nzcv
; CHECK: %select:gpr64 = CSINCXr %t, %reg1, 1, implicit $nzcv
; CHECK: $x0 = COPY %select
; CHECK: RET_ReallyLR implicit $x0
%reg0:gpr(s64) = COPY $x0
%reg1:gpr(p0) = COPY $x1
%cond:gpr(s1) = G_TRUNC %reg0(s64)
%t:gpr(p0) = COPY $x2
%one:gpr(s64) = G_CONSTANT i64 1
%ptr_add:gpr(p0) = G_PTR_ADD %reg1(p0), %one
%select:gpr(p0) = G_SELECT %cond(s1), %t, %ptr_add
$x0 = COPY %select(p0)
RET_ReallyLR implicit $x0
...
---
name: binop_dont_optimize_twice