[llvm] r296933 - [x86] check for commuted add pattern to find ADC/SBB
Sanjay Patel via llvm-commits
llvm-commits at lists.llvm.org
Fri Mar 3 16:18:32 PST 2017
Author: spatel
Date: Fri Mar 3 18:18:31 2017
New Revision: 296933
URL: http://llvm.org/viewvc/llvm-project?rev=296933&view=rev
Log:
[x86] check for commuted add pattern to find ADC/SBB
Modified:
llvm/trunk/lib/Target/X86/X86ISelLowering.cpp
llvm/trunk/test/CodeGen/X86/conditional-indecrement.ll
Modified: llvm/trunk/lib/Target/X86/X86ISelLowering.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/X86/X86ISelLowering.cpp?rev=296933&r1=296932&r2=296933&view=diff
==============================================================================
--- llvm/trunk/lib/Target/X86/X86ISelLowering.cpp (original)
+++ llvm/trunk/lib/Target/X86/X86ISelLowering.cpp Fri Mar 3 18:18:31 2017
@@ -34106,7 +34106,15 @@ static SDValue combineADC(SDNode *N, Sel
static SDValue combineAddOrSubToADCOrSBB(SDNode *N, SelectionDAG &DAG) {
// Look through ZExts.
bool IsSub = N->getOpcode() == ISD::SUB;
- SDValue Ext = N->getOperand(IsSub ? 1 : 0);
+ SDValue Y = N->getOperand(0);
+ SDValue Ext = N->getOperand(1);
+
+ // If this is an add, canonicalize a zext to the RHS.
+ // TODO: Incomplete? What if both sides are zexts?
+ if (!IsSub && Ext.getOpcode() != ISD::ZERO_EXTEND &&
+ Y.getOpcode() == ISD::ZERO_EXTEND)
+ std::swap(Ext, Y);
+
if (Ext.getOpcode() != ISD::ZERO_EXTEND || !Ext.hasOneUse())
return SDValue();
@@ -34130,17 +34138,16 @@ static SDValue combineAddOrSubToADCOrSBB
SDValue NewCmp = DAG.getNode(X86ISD::CMP, DL, MVT::i32, X,
DAG.getConstant(1, DL, X.getValueType()));
- SDValue Y = N->getOperand(IsSub ? 0 : 1);
EVT VT = Y.getValueType();
// Y - (X != 0) --> sub Y, (zext(setne X, 0)) --> adc Y, -1, (cmp X, 1)
- // (X != 0) + Y --> add (zext(setne X, 0)), Y --> sbb Y, -1, (cmp X, 1)
+ // Y + (X != 0) --> add Y, (zext(setne X, 0)) --> sbb Y, -1, (cmp X, 1)
if (CC == X86::COND_NE)
return DAG.getNode(IsSub ? X86ISD::ADC : X86ISD::SBB, DL, VT, Y,
DAG.getConstant(-1ULL, DL, VT), NewCmp);
// Y - (X == 0) --> sub Y, (zext(sete X, 0)) --> sbb Y, 0, (cmp X, 1)
- // (X == 0) + Y --> add (zext(sete X, 0)), Y --> adc Y, 0, (cmp X, 1)
+ // Y + (X == 0) --> add Y, (zext(sete X, 0)) --> adc Y, 0, (cmp X, 1)
return DAG.getNode(IsSub ? X86ISD::SBB : X86ISD::ADC, DL, VT, Y,
DAG.getConstant(0, DL, VT), NewCmp);
}
Modified: llvm/trunk/test/CodeGen/X86/conditional-indecrement.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/CodeGen/X86/conditional-indecrement.ll?rev=296933&r1=296932&r2=296933&view=diff
==============================================================================
--- llvm/trunk/test/CodeGen/X86/conditional-indecrement.ll (original)
+++ llvm/trunk/test/CodeGen/X86/conditional-indecrement.ll Fri Mar 3 18:18:31 2017
@@ -17,10 +17,9 @@ define i32 @test1(i32 %a, i32 %b) nounwi
define i32 @test1_commute(i32 %a, i32 %b) nounwind readnone {
; CHECK-LABEL: test1_commute:
; CHECK: # BB#0:
-; CHECK-NEXT: xorl %eax, %eax
-; CHECK-NEXT: testl %edi, %edi
-; CHECK-NEXT: setne %al
-; CHECK-NEXT: addl %esi, %eax
+; CHECK-NEXT: cmpl $1, %edi
+; CHECK-NEXT: sbbl $-1, %esi
+; CHECK-NEXT: movl %esi, %eax
; CHECK-NEXT: retq
%cmp = icmp ne i32 %a, 0
%inc = zext i1 %cmp to i32
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