[llvm] r225591 - Fix PR22179.
Sanjoy Das
sanjoy at playingwithpointers.com
Sat Jan 10 15:41:25 PST 2015
Author: sanjoy
Date: Sat Jan 10 17:41:24 2015
New Revision: 225591
URL: http://llvm.org/viewvc/llvm-project?rev=225591&view=rev
Log:
Fix PR22179.
We were incorrectly inferring nsw for certain SCEVs. We can be more
aggressive here (see Richard Smith's comment on
http://llvm.org/bugs/show_bug.cgi?id=22179) but this change just
focuses on correctness.
Differential Revision: http://reviews.llvm.org/D6914
Added:
llvm/trunk/test/Analysis/ScalarEvolution/pr22179.ll
Modified:
llvm/trunk/lib/Analysis/ScalarEvolution.cpp
llvm/trunk/test/CodeGen/AArch64/arm64-scaled_iv.ll
llvm/trunk/test/CodeGen/X86/avoid_complex_am.ll
Modified: llvm/trunk/lib/Analysis/ScalarEvolution.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Analysis/ScalarEvolution.cpp?rev=225591&r1=225590&r2=225591&view=diff
==============================================================================
--- llvm/trunk/lib/Analysis/ScalarEvolution.cpp (original)
+++ llvm/trunk/lib/Analysis/ScalarEvolution.cpp Sat Jan 10 17:41:24 2015
@@ -1737,6 +1737,36 @@ namespace {
};
}
+// We're trying to construct a SCEV of type `Type' with `Ops' as operands and
+// `OldFlags' as can't-wrap behavior. Infer a more aggressive set of
+// can't-overflow flags for the operation if possible.
+static SCEV::NoWrapFlags
+StrengthenNoWrapFlags(ScalarEvolution *SE, SCEVTypes Type,
+ const SmallVectorImpl<const SCEV *> &Ops,
+ SCEV::NoWrapFlags OldFlags) {
+ using namespace std::placeholders;
+
+ bool CanAnalyze =
+ Type == scAddExpr || Type == scAddRecExpr || Type == scMulExpr;
+ (void)CanAnalyze;
+ assert(CanAnalyze && "don't call from other places!");
+
+ int SignOrUnsignMask = SCEV::FlagNUW | SCEV::FlagNSW;
+ SCEV::NoWrapFlags SignOrUnsignWrap =
+ ScalarEvolution::maskFlags(OldFlags, SignOrUnsignMask);
+
+ // If FlagNSW is true and all the operands are non-negative, infer FlagNUW.
+ auto IsKnownNonNegative =
+ std::bind(std::mem_fn(&ScalarEvolution::isKnownNonNegative), SE, _1);
+
+ if (SignOrUnsignWrap == SCEV::FlagNSW &&
+ std::all_of(Ops.begin(), Ops.end(), IsKnownNonNegative))
+ return ScalarEvolution::setFlags(OldFlags,
+ (SCEV::NoWrapFlags)SignOrUnsignMask);
+
+ return OldFlags;
+}
+
/// getAddExpr - Get a canonical add expression, or something simpler if
/// possible.
const SCEV *ScalarEvolution::getAddExpr(SmallVectorImpl<const SCEV *> &Ops,
@@ -1752,20 +1782,7 @@ const SCEV *ScalarEvolution::getAddExpr(
"SCEVAddExpr operand types don't match!");
#endif
- // If FlagNSW is true and all the operands are non-negative, infer FlagNUW.
- // And vice-versa.
- int SignOrUnsignMask = SCEV::FlagNUW | SCEV::FlagNSW;
- SCEV::NoWrapFlags SignOrUnsignWrap = maskFlags(Flags, SignOrUnsignMask);
- if (SignOrUnsignWrap && (SignOrUnsignWrap != SignOrUnsignMask)) {
- bool All = true;
- for (SmallVectorImpl<const SCEV *>::const_iterator I = Ops.begin(),
- E = Ops.end(); I != E; ++I)
- if (!isKnownNonNegative(*I)) {
- All = false;
- break;
- }
- if (All) Flags = setFlags(Flags, (SCEV::NoWrapFlags)SignOrUnsignMask);
- }
+ Flags = StrengthenNoWrapFlags(this, scAddExpr, Ops, Flags);
// Sort by complexity, this groups all similar expression types together.
GroupByComplexity(Ops, LI);
@@ -2174,20 +2191,7 @@ const SCEV *ScalarEvolution::getMulExpr(
"SCEVMulExpr operand types don't match!");
#endif
- // If FlagNSW is true and all the operands are non-negative, infer FlagNUW.
- // And vice-versa.
- int SignOrUnsignMask = SCEV::FlagNUW | SCEV::FlagNSW;
- SCEV::NoWrapFlags SignOrUnsignWrap = maskFlags(Flags, SignOrUnsignMask);
- if (SignOrUnsignWrap && (SignOrUnsignWrap != SignOrUnsignMask)) {
- bool All = true;
- for (SmallVectorImpl<const SCEV *>::const_iterator I = Ops.begin(),
- E = Ops.end(); I != E; ++I)
- if (!isKnownNonNegative(*I)) {
- All = false;
- break;
- }
- if (All) Flags = setFlags(Flags, (SCEV::NoWrapFlags)SignOrUnsignMask);
- }
+ Flags = StrengthenNoWrapFlags(this, scMulExpr, Ops, Flags);
// Sort by complexity, this groups all similar expression types together.
GroupByComplexity(Ops, LI);
@@ -2653,20 +2657,7 @@ ScalarEvolution::getAddRecExpr(SmallVect
// meaningful BE count at this point (and if we don't, we'd be stuck
// with a SCEVCouldNotCompute as the cached BE count).
- // If FlagNSW is true and all the operands are non-negative, infer FlagNUW.
- // And vice-versa.
- int SignOrUnsignMask = SCEV::FlagNUW | SCEV::FlagNSW;
- SCEV::NoWrapFlags SignOrUnsignWrap = maskFlags(Flags, SignOrUnsignMask);
- if (SignOrUnsignWrap && (SignOrUnsignWrap != SignOrUnsignMask)) {
- bool All = true;
- for (SmallVectorImpl<const SCEV *>::const_iterator I = Operands.begin(),
- E = Operands.end(); I != E; ++I)
- if (!isKnownNonNegative(*I)) {
- All = false;
- break;
- }
- if (All) Flags = setFlags(Flags, (SCEV::NoWrapFlags)SignOrUnsignMask);
- }
+ Flags = StrengthenNoWrapFlags(this, scAddRecExpr, Operands, Flags);
// Canonicalize nested AddRecs in by nesting them in order of loop depth.
if (const SCEVAddRecExpr *NestedAR = dyn_cast<SCEVAddRecExpr>(Operands[0])) {
Added: llvm/trunk/test/Analysis/ScalarEvolution/pr22179.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Analysis/ScalarEvolution/pr22179.ll?rev=225591&view=auto
==============================================================================
--- llvm/trunk/test/Analysis/ScalarEvolution/pr22179.ll (added)
+++ llvm/trunk/test/Analysis/ScalarEvolution/pr22179.ll Sat Jan 10 17:41:24 2015
@@ -0,0 +1,28 @@
+; RUN: opt -analyze -scalar-evolution < %s | FileCheck %s
+
+%struct.anon = type { i8 }
+%struct.S = type { i32 }
+
+ at a = common global %struct.anon zeroinitializer, align 1
+ at b = common global %struct.S zeroinitializer, align 4
+
+; Function Attrs: nounwind ssp uwtable
+define i32 @main() {
+; CHECK-LABEL: Classifying expressions for: @main
+ store i8 0, i8* getelementptr inbounds (%struct.anon* @a, i64 0, i32 0), align 1
+ br label %loop
+
+loop:
+ %storemerge1 = phi i8 [ 0, %0 ], [ %inc, %loop ]
+ %m = load volatile i32* getelementptr inbounds (%struct.S* @b, i64 0, i32 0), align 4
+ %inc = add nuw i8 %storemerge1, 1
+; CHECK: %inc = add nuw i8 %storemerge1, 1
+; CHECK-NEXT: --> {1,+,1}<nuw><%loop>
+; CHECK-NOT: --> {1,+,1}<nuw><nsw><%loop>
+ %exitcond = icmp eq i8 %inc, -128
+ br i1 %exitcond, label %exit, label %loop
+
+exit:
+ store i8 -128, i8* getelementptr inbounds (%struct.anon* @a, i64 0, i32 0), align 1
+ ret i32 0
+}
Modified: llvm/trunk/test/CodeGen/AArch64/arm64-scaled_iv.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/CodeGen/AArch64/arm64-scaled_iv.ll?rev=225591&r1=225590&r2=225591&view=diff
==============================================================================
--- llvm/trunk/test/CodeGen/AArch64/arm64-scaled_iv.ll (original)
+++ llvm/trunk/test/CodeGen/AArch64/arm64-scaled_iv.ll Sat Jan 10 17:41:24 2015
@@ -20,7 +20,7 @@ for.body:
%arrayidx = getelementptr inbounds double* %b, i64 %tmp
%tmp1 = load double* %arrayidx, align 8
; The induction variable should carry the scaling factor: 1 * 8 = 8.
-; CHECK: [[IVNEXT]] = add nuw nsw i64 [[IV]], 8
+; CHECK: [[IVNEXT]] = add nuw i64 [[IV]], 8
%indvars.iv.next = add i64 %indvars.iv, 1
%arrayidx2 = getelementptr inbounds double* %c, i64 %indvars.iv.next
%tmp2 = load double* %arrayidx2, align 8
Modified: llvm/trunk/test/CodeGen/X86/avoid_complex_am.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/CodeGen/X86/avoid_complex_am.ll?rev=225591&r1=225590&r2=225591&view=diff
==============================================================================
--- llvm/trunk/test/CodeGen/X86/avoid_complex_am.ll (original)
+++ llvm/trunk/test/CodeGen/X86/avoid_complex_am.ll Sat Jan 10 17:41:24 2015
@@ -22,7 +22,7 @@ for.body:
%arrayidx = getelementptr inbounds double* %b, i64 %tmp
%tmp1 = load double* %arrayidx, align 8
; The induction variable should carry the scaling factor: 1.
-; CHECK: [[IVNEXT]] = add nuw nsw i64 [[IV]], 1
+; CHECK: [[IVNEXT]] = add nuw i64 [[IV]], 1
%indvars.iv.next = add i64 %indvars.iv, 1
%arrayidx2 = getelementptr inbounds double* %c, i64 %indvars.iv.next
%tmp2 = load double* %arrayidx2, align 8
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