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[DAG] canCreateUndefOrPoison - add freeze(sext(x)) -> sext(freeze(x)) and freeze(zext(x)) -> zext(freeze(x)) support 

Both are guaranteed not to create undef/poison
This commit is contained in:
Simon Pilgrim 2022-08-08 16:43:30 +01:00
parent 9b031d5e3a
commit e4b2c52420
2 changed files with 5 additions and 10 deletions
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2
llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
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@ -4560,6 +4560,8 @@ bool SelectionDAG::canCreateUndefOrPoison(SDValue Op, const APInt &DemandedElts,
unsigned Opcode = Op.getOpcode();
switch (Opcode) {
case ISD::SIGN_EXTEND:
case ISD::ZERO_EXTEND:
case ISD::BITCAST:
case ISD::FREEZE:
return false;

13
llvm/test/CodeGen/X86/freeze-unary.ll
View File

@ -6,13 +6,11 @@ define i32 @freeze_sext(i8 %a0) nounwind {
; X86-LABEL: freeze_sext:
; X86: # %bb.0:
; X86-NEXT: movsbl {{[0-9]+}}(%esp), %eax
; X86-NEXT: cwtl
; X86-NEXT: retl
;
; X64-LABEL: freeze_sext:
; X64: # %bb.0:
; X64-NEXT: movsbl %dil, %eax
; X64-NEXT: cwtl
; X64-NEXT: retq
%x = sext i8 %a0 to i16
%y = freeze i16 %x
@ -24,15 +22,13 @@ define <4 x i32> @freeze_sext_vec(<4 x i8> %a0) nounwind {
; X86-LABEL: freeze_sext_vec:
; X86: # %bb.0:
; X86-NEXT: punpcklbw {{.*#+}} xmm0 = xmm0[0,0,1,1,2,2,3,3,4,4,5,5,6,6,7,7]
; X86-NEXT: psraw $8, %xmm0
; X86-NEXT: punpcklwd {{.*#+}} xmm0 = xmm0[0,0,1,1,2,2,3,3]
; X86-NEXT: psrad $16, %xmm0
; X86-NEXT: psrad $24, %xmm0
; X86-NEXT: retl
;
; X64-LABEL: freeze_sext_vec:
; X64: # %bb.0:
; X64-NEXT: pmovsxbw %xmm0, %xmm0
; X64-NEXT: pmovsxwd %xmm0, %xmm0
; X64-NEXT: pmovsxbd %xmm0, %xmm0
; X64-NEXT: retq
%x = sext <4 x i8> %a0 to <4 x i16>
%y = freeze <4 x i16> %x
@ -44,13 +40,11 @@ define i32 @freeze_zext(i8 %a0) nounwind {
; X86-LABEL: freeze_zext:
; X86: # %bb.0:
; X86-NEXT: movzbl {{[0-9]+}}(%esp), %eax
; X86-NEXT: movzwl %ax, %eax
; X86-NEXT: retl
;
; X64-LABEL: freeze_zext:
; X64: # %bb.0:
; X64-NEXT: movzbl %dil, %eax
; X64-NEXT: movzwl %ax, %eax
; X64-NEXT: retq
%x = zext i8 %a0 to i16
%y = freeze i16 %x
@ -68,8 +62,7 @@ define <2 x i64> @freeze_zext_vec(<2 x i16> %a0) nounwind {
;
; X64-LABEL: freeze_zext_vec:
; X64: # %bb.0:
; X64-NEXT: pmovzxwd {{.*#+}} xmm0 = xmm0[0],zero,xmm0[1],zero,xmm0[2],zero,xmm0[3],zero
; X64-NEXT: pmovzxdq {{.*#+}} xmm0 = xmm0[0],zero,xmm0[1],zero
; X64-NEXT: pmovzxwq {{.*#+}} xmm0 = xmm0[0],zero,zero,zero,xmm0[1],zero,zero,zero
; X64-NEXT: retq
%x = zext <2 x i16> %a0 to <2 x i32>
%y = freeze <2 x i32> %x