RPCS3/llvm-mirror
1
0
Fork 0
mirror of https://github.com/RPCS3/llvm-mirror.git synced 2025-01-31 12:41:49 +01:00
Code Issues Projects Releases Wiki Activity

[GlobalISel] Look through extends etc in CombinerHelper::matchConstantOp

Browse Source 
It's possible to end up with a zext or something in the way of a G_CONSTANT,
even pre-legalization. This can happen with memsets.

e.g.

https://godbolt.org/z/Bjc8cw

To make sure we can catch these cases, use `getConstantVRegValWithLookThrough`
instead of `mi_match`.

Differential Revision: https://reviews.llvm.org/D81875
This commit is contained in:
Jessica Paquette 2020-06-15 12:16:33 -07:00
parent cec0aa2b18
commit ff5c742e1e
2 changed files with 23 additions and 2 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

5
lib/CodeGen/GlobalISel/CombinerHelper.cpp
View File

@ -1617,8 +1617,9 @@ bool CombinerHelper::matchEqualDefs(const MachineOperand &MOP1,
bool CombinerHelper::matchConstantOp(const MachineOperand &MOP, int64_t C) {
if (!MOP.isReg())
return false;
int64_t Cst;
return mi_match(MOP.getReg(), MRI, m_ICst(Cst)) && Cst == C;
// MIPatternMatch doesn't let us look through G_ZEXT etc.
auto ValAndVReg = getConstantVRegValWithLookThrough(MOP.getReg(), MRI);
return ValAndVReg && ValAndVReg->Value == C;
}
bool CombinerHelper::replaceSingleDefInstWithOperand(MachineInstr &MI,

20
test/CodeGen/AArch64/GlobalISel/prelegalizercombiner-trivial-arith.mir
View File

@ -286,4 +286,24 @@ body: |
%op:_(s32) = G_SUB %x(s32), %cst
$w0 = COPY %op(s32)
RET_ReallyLR implicit $w0
...
---
name: look_through_zext
tracksRegLiveness: true
body: |
bb.0:
liveins: $x0
; CHECK-LABEL: name: look_through_zext
; CHECK: liveins: $x0
; CHECK: %zero:_(s8) = G_CONSTANT i8 0
; CHECK: %zext_zero:_(s64) = G_ZEXT %zero(s8)
; CHECK: $x0 = COPY %zext_zero(s64)
; CHECK: RET_ReallyLR implicit $x0
%zero:_(s8) = G_CONSTANT i8 0
%zext_zero:_(s64) = G_ZEXT %zero(s8)
%c:_(s64) = G_CONSTANT i64 72340172838076673
%mul:_(s64) = G_MUL %c, %zext_zero
$x0 = COPY %mul(s64)
RET_ReallyLR implicit $x0
...