[llvm] 20bf0cf - [TargetLowering] optimizeSetCCToComparisonWithZero(): add extra sanity checks (PR43769)
Roman Lebedev via llvm-commits
llvm-commits at lists.llvm.org
Wed Oct 23 02:02:33 PDT 2019
Author: Roman Lebedev
Date: 2019-10-23T12:01:40+03:00
New Revision: 20bf0cf2f020ce3b344838b88d8a86e156c05443
URL: https://github.com/llvm/llvm-project/commit/20bf0cf2f020ce3b344838b88d8a86e156c05443
DIFF: https://github.com/llvm/llvm-project/commit/20bf0cf2f020ce3b344838b88d8a86e156c05443.diff
LOG: [TargetLowering] optimizeSetCCToComparisonWithZero(): add extra sanity checks (PR43769)
We should do the fold only if both constants are plain,
non-opaque constants, at least that is the DAG.FoldConstantArithmetic()
requirement.
And if the constant we are comparing with is zero - we shouldn't be
trying to do this fold in the first place.
Fixes https://bugs.llvm.org/show_bug.cgi?id=43769
Added:
llvm/test/CodeGen/X86/pr43769.ll
Modified:
llvm/lib/CodeGen/SelectionDAG/TargetLowering.cpp
Removed:
################################################################################
diff --git a/llvm/lib/CodeGen/SelectionDAG/TargetLowering.cpp b/llvm/lib/CodeGen/SelectionDAG/TargetLowering.cpp
index c0b846adc040..5af2663d29e5 100644
--- a/llvm/lib/CodeGen/SelectionDAG/TargetLowering.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/TargetLowering.cpp
@@ -3052,6 +3052,10 @@ SDValue TargetLowering::optimizeSetCCToComparisonWithZero(
assert((Cond == ISD::SETEQ || Cond == ISD::SETNE) &&
"Only for equality-comparisons.");
+ // The constant we are comparing with must be a non-zero, non-opaque constant.
+ if (N1C->isNullValue() || N1C->isOpaque())
+ return SDValue();
+
// LHS should not be used elsewhere, to avoid creating an extra node.
if (!N0.hasOneUse())
return SDValue();
@@ -3072,9 +3076,9 @@ SDValue TargetLowering::optimizeSetCCToComparisonWithZero(
break;
}
- // Second operand must be a constant.
+ // Second operand must be a non-opaque constant.
ConstantSDNode *N01C = isConstOrConstSplat(N0.getOperand(1));
- if (!N01C)
+ if (!N01C || N01C->isOpaque())
return SDValue();
// And let's be even more specific for now, it must be a zero constant.
diff --git a/llvm/test/CodeGen/X86/pr43769.ll b/llvm/test/CodeGen/X86/pr43769.ll
new file mode 100644
index 000000000000..fb6cd95c5325
--- /dev/null
+++ b/llvm/test/CodeGen/X86/pr43769.ll
@@ -0,0 +1,54 @@
+; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py
+; RUN: llc -mtriple=i686-w64-windows-gnu %s -o - | FileCheck %s
+
+; Reduced from https://bugs.llvm.org/show_bug.cgi?id=43769
+
+define i32 @b(i32 %a, i32* %c, i32 %d) {
+; CHECK-LABEL: b:
+; CHECK: # %bb.0: # %entry
+; CHECK-NEXT: cmpl $0, {{[0-9]+}}(%esp)
+; CHECK-NEXT: je LBB0_4
+; CHECK-NEXT: # %bb.1: # %for.body.lr.ph
+; CHECK-NEXT: movl {{[0-9]+}}(%esp), %eax
+; CHECK-NEXT: movl %eax, %ecx
+; CHECK-NEXT: sarl $31, %ecx
+; CHECK-NEXT: addl $-2147483647, %eax # imm = 0x80000001
+; CHECK-NEXT: adcl $0, %ecx
+; CHECK-NEXT: jne LBB0_4
+; CHECK-NEXT: # %bb.2: # %for.body.lr.ph.peel.newph
+; CHECK-NEXT: movl {{[0-9]+}}(%esp), %ecx
+; CHECK-NEXT: movl $-2147483647, %edx # imm = 0x80000001
+; CHECK-NEXT: movl %ecx, %eax
+; CHECK-NEXT: sarl $31, %eax
+; CHECK-NEXT: addl %ecx, %edx
+; CHECK-NEXT: adcl $0, %eax
+; CHECK-NEXT: .p2align 4, 0x90
+; CHECK-NEXT: LBB0_3: # %for.body
+; CHECK-NEXT: # =>This Inner Loop Header: Depth=1
+; CHECK-NEXT: testl %eax, %eax
+; CHECK-NEXT: je LBB0_3
+; CHECK-NEXT: LBB0_4: # %for.end
+; CHECK-NEXT: retl
+entry:
+ %tobool3 = icmp eq i32 %a, 0
+ br i1 %tobool3, label %for.end, label %for.body.lr.ph
+
+for.body.lr.ph: ; preds = %entry
+ %0 = ptrtoint i32* %c to i32
+ %conv.peel = sext i32 %d to i64
+ %add.peel = add nsw i64 %conv.peel, 2147483649
+ %tobool1.peel = icmp ugt i64 %add.peel, 4294967295
+ br i1 %tobool1.peel, label %for.end, label %for.body.lr.ph.peel.newph
+
+for.body.lr.ph.peel.newph: ; preds = %for.body.lr.ph
+ %conv = sext i32 %0 to i64
+ %add = add nsw i64 %conv, 2147483649
+ %tobool1 = icmp ugt i64 %add, 4294967295
+ br label %for.body
+
+for.body: ; preds = %for.body, %for.body.lr.ph.peel.newph
+ br i1 %tobool1, label %for.end, label %for.body
+
+for.end: ; preds = %for.body.lr.ph, %for.body, %entry
+ ret i32 undef
+}
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