When gvn decides to replace an instruction with another, we have to patch the

replacement to make it at least as generic as the instruction being replaced.
This includes:
* dropping nsw/nuw flags
* getting the least restrictive tbaa and fpmath metadata
* merging ranges

Fixes PR12979.

llvm-svn: 157958
This commit is contained in:
Rafael Espindola 2012-06-04 22:44:21 +00:00
parent 17fcb85c11
commit f2cb55e405
5 changed files with 506 additions and 2 deletions

View File

@ -19,6 +19,7 @@
#include "llvm/Transforms/Scalar.h"
#include "llvm/GlobalVariable.h"
#include "llvm/IntrinsicInst.h"
#include "llvm/Metadata.h"
#include "llvm/LLVMContext.h"
#include "llvm/Analysis/AliasAnalysis.h"
#include "llvm/Analysis/ConstantFolding.h"
@ -41,6 +42,7 @@
#include "llvm/ADT/Statistic.h"
#include "llvm/Support/Allocator.h"
#include "llvm/Support/CommandLine.h"
#include "llvm/Support/ConstantRange.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/IRBuilder.h"
#include "llvm/Support/PatternMatch.h"
@ -1734,6 +1736,202 @@ bool GVN::processNonLocalLoad(LoadInst *LI) {
return true;
}
static MDNode *getMostGenericTBAA(MDNode *A, MDNode *B) {
if (!A || !B)
return NULL;
if (A == B)
return A;
SmallVector<MDNode *, 4> PathA;
MDNode *T = A;
while (T) {
PathA.push_back(T);
T = T->getNumOperands() >= 2 ? cast_or_null<MDNode>(T->getOperand(1)) : 0;
}
SmallVector<MDNode *, 4> PathB;
T = B;
while (T) {
PathB.push_back(T);
T = T->getNumOperands() >= 2 ? cast_or_null<MDNode>(T->getOperand(1)) : 0;
}
int IA = PathA.size() - 1;
int IB = PathB.size() - 1;
MDNode *Ret = 0;
while (IA >= 0 && IB >=0) {
if (PathA[IA] == PathB[IB])
Ret = PathA[IA];
else
break;
--IA;
--IB;
}
return Ret;
}
static MDNode *getMostGenericFPMath(MDNode *A, MDNode *B) {
if (!A || !B)
return NULL;
APFloat AVal = cast<ConstantFP>(A->getOperand(0))->getValueAPF();
APFloat BVal = cast<ConstantFP>(B->getOperand(0))->getValueAPF();
if (AVal.compare(BVal) == APFloat::cmpLessThan)
return A;
return B;
}
static bool isContiguous(const ConstantRange &A, const ConstantRange &B) {
return A.getUpper() == B.getLower() || A.getLower() == B.getUpper();
}
static bool canBeMerged(const ConstantRange &A, const ConstantRange &B) {
return !A.intersectWith(B).isEmptySet() || isContiguous(A, B);
}
static bool tryMergeRange(SmallVector<Value*, 4> &EndPoints, ConstantInt *Low,
ConstantInt *High) {
ConstantRange NewRange(Low->getValue(), High->getValue());
unsigned Size = EndPoints.size();
APInt LB = cast<ConstantInt>(EndPoints[Size - 2])->getValue();
APInt LE = cast<ConstantInt>(EndPoints[Size - 1])->getValue();
ConstantRange LastRange(LB, LE);
if (canBeMerged(NewRange, LastRange)) {
ConstantRange Union = LastRange.unionWith(NewRange);
Type *Ty = High->getType();
EndPoints[Size - 2] = ConstantInt::get(Ty, Union.getLower());
EndPoints[Size - 1] = ConstantInt::get(Ty, Union.getUpper());
return true;
}
return false;
}
static void addRange(SmallVector<Value*, 4> &EndPoints, ConstantInt *Low,
ConstantInt *High) {
if (!EndPoints.empty())
if (tryMergeRange(EndPoints, Low, High))
return;
EndPoints.push_back(Low);
EndPoints.push_back(High);
}
static MDNode *getMostGenericRange(MDNode *A, MDNode *B) {
// Given two ranges, we want to compute the union of the ranges. This
// is slightly complitade by having to combine the intervals and merge
// the ones that overlap.
if (!A || !B)
return NULL;
if (A == B)
return A;
// First, walk both lists in older of the lower boundary of each interval.
// At each step, try to merge the new interval to the last one we adedd.
SmallVector<Value*, 4> EndPoints;
int AI = 0;
int BI = 0;
int AN = A->getNumOperands() / 2;
int BN = B->getNumOperands() / 2;
while (AI < AN && BI < BN) {
ConstantInt *ALow = cast<ConstantInt>(A->getOperand(2 * AI));
ConstantInt *BLow = cast<ConstantInt>(B->getOperand(2 * BI));
if (ALow->getValue().slt(BLow->getValue())) {
addRange(EndPoints, ALow, cast<ConstantInt>(A->getOperand(2 * AI + 1)));
++AI;
} else {
addRange(EndPoints, BLow, cast<ConstantInt>(B->getOperand(2 * BI + 1)));
++BI;
}
}
while (AI < AN) {
addRange(EndPoints, cast<ConstantInt>(A->getOperand(2 * AI)),
cast<ConstantInt>(A->getOperand(2 * AI + 1)));
++AI;
}
while (BI < BN) {
addRange(EndPoints, cast<ConstantInt>(B->getOperand(2 * BI)),
cast<ConstantInt>(B->getOperand(2 * BI + 1)));
++BI;
}
// If we have more than 2 ranges (4 endpoints) we have to try to merge
// the last and first ones.
unsigned Size = EndPoints.size();
if (Size > 4) {
ConstantInt *FB = cast<ConstantInt>(EndPoints[0]);
ConstantInt *FE = cast<ConstantInt>(EndPoints[1]);
if (tryMergeRange(EndPoints, FB, FE)) {
for (unsigned i = 0; i < Size - 2; ++i) {
EndPoints[i] = EndPoints[i + 2];
}
EndPoints.resize(Size - 2);
}
}
// If in the end we have a single range, it is possible that it is now the
// full range. Just drop the metadata in that case.
if (EndPoints.size() == 2) {
ConstantRange Range(cast<ConstantInt>(EndPoints[0])->getValue(),
cast<ConstantInt>(EndPoints[1])->getValue());
if (Range.isFullSet())
return NULL;
}
return MDNode::get(A->getContext(), EndPoints);
}
static void patchReplacementInstruction(Value *Repl, Instruction *I) {
// Patch the replacement so that it is not more restrictive than the value
// being replaced.
BinaryOperator *Op = dyn_cast<BinaryOperator>(I);
BinaryOperator *ReplOp = dyn_cast<BinaryOperator>(Repl);
if (Op && ReplOp && isa<OverflowingBinaryOperator>(Op) &&
isa<OverflowingBinaryOperator>(ReplOp)) {
if (ReplOp->hasNoSignedWrap() && !Op->hasNoSignedWrap())
ReplOp->setHasNoSignedWrap(false);
if (ReplOp->hasNoUnsignedWrap() && !Op->hasNoUnsignedWrap())
ReplOp->setHasNoUnsignedWrap(false);
}
if (Instruction *ReplInst = dyn_cast<Instruction>(Repl)) {
SmallVector<std::pair<unsigned, MDNode*>, 4> Metadata;
ReplInst->getAllMetadataOtherThanDebugLoc(Metadata);
for (int i = 0, n = Metadata.size(); i < n; ++i) {
unsigned Kind = Metadata[i].first;
MDNode *IMD = I->getMetadata(Kind);
MDNode *ReplMD = Metadata[i].second;
switch(Kind) {
default:
ReplInst->setMetadata(Kind, NULL); // Remove unknown metadata
break;
case LLVMContext::MD_dbg:
llvm_unreachable("getAllMetadataOtherThanDebugLoc returned a MD_dbg");
case LLVMContext::MD_tbaa:
ReplInst->setMetadata(Kind, getMostGenericTBAA(IMD, ReplMD));
break;
case LLVMContext::MD_range:
ReplInst->setMetadata(Kind, getMostGenericRange(IMD, ReplMD));
break;
case LLVMContext::MD_prof:
llvm_unreachable("MD_prof in a non terminator instruction");
break;
case LLVMContext::MD_fpmath:
ReplInst->setMetadata(Kind, getMostGenericFPMath(IMD, ReplMD));
break;
}
}
}
}
static void patchAndReplaceAllUsesWith(Value *Repl, Instruction *I) {
patchReplacementInstruction(Repl, I);
I->replaceAllUsesWith(Repl);
}
/// processLoad - Attempt to eliminate a load, first by eliminating it
/// locally, and then attempting non-local elimination if that fails.
bool GVN::processLoad(LoadInst *L) {
@ -1892,7 +2090,7 @@ bool GVN::processLoad(LoadInst *L) {
}
// Remove it!
L->replaceAllUsesWith(AvailableVal);
patchAndReplaceAllUsesWith(AvailableVal, L);
if (DepLI->getType()->isPointerTy())
MD->invalidateCachedPointerInfo(DepLI);
markInstructionForDeletion(L);
@ -2224,7 +2422,7 @@ bool GVN::processInstruction(Instruction *I) {
}
// Remove it!
I->replaceAllUsesWith(repl);
patchAndReplaceAllUsesWith(repl, I);
if (MD && repl->getType()->isPointerTy())
MD->invalidateCachedPointerInfo(repl);
markInstructionForDeletion(I);

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@ -0,0 +1,45 @@
; RUN: opt %s -gvn -S -o - | FileCheck %s
define double @test1(double %x, double %y) {
; CHECK: @test1(double %x, double %y)
; CHECK: %add1 = fadd double %x, %y
; CHECK-NOT: fpmath
; CHECK: %foo = fadd double %add1, %add1
%add1 = fadd double %x, %y, !fpmath !0
%add2 = fadd double %x, %y
%foo = fadd double %add1, %add2
ret double %foo
}
define double @test2(double %x, double %y) {
; CHECK: @test2(double %x, double %y)
; CHECK: %add1 = fadd double %x, %y, !fpmath !0
; CHECK: %foo = fadd double %add1, %add1
%add1 = fadd double %x, %y, !fpmath !0
%add2 = fadd double %x, %y, !fpmath !0
%foo = fadd double %add1, %add2
ret double %foo
}
define double @test3(double %x, double %y) {
; CHECK: @test3(double %x, double %y)
; CHECK: %add1 = fadd double %x, %y, !fpmath !1
; CHECK: %foo = fadd double %add1, %add1
%add1 = fadd double %x, %y, !fpmath !1
%add2 = fadd double %x, %y, !fpmath !0
%foo = fadd double %add1, %add2
ret double %foo
}
define double @test4(double %x, double %y) {
; CHECK: @test4(double %x, double %y)
; CHECK: %add1 = fadd double %x, %y, !fpmath !1
; CHECK: %foo = fadd double %add1, %add1
%add1 = fadd double %x, %y, !fpmath !0
%add2 = fadd double %x, %y, !fpmath !1
%foo = fadd double %add1, %add2
ret double %foo
}
!0 = metadata !{ float 5.0 }
!1 = metadata !{ float 2.5 }

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@ -0,0 +1,79 @@
; RUN: opt %s -gvn -S -o - | FileCheck %s
define i32 @test1(i32 %x, i32 %y) {
; CHECK: @test1(i32 %x, i32 %y)
; CHECK: %add1 = add i32 %x, %y
; CHECK: %foo = add i32 %add1, %add1
%add1 = add nsw i32 %x, %y
%add2 = add i32 %x, %y
%foo = add i32 %add1, %add2
ret i32 %foo
}
define i32 @test2(i32 %x, i32 %y) {
; CHECK: @test2(i32 %x, i32 %y)
; CHECK: %add1 = add i32 %x, %y
; CHECK: %foo = add i32 %add1, %add1
%add1 = add nuw i32 %x, %y
%add2 = add i32 %x, %y
%foo = add i32 %add1, %add2
ret i32 %foo
}
define i32 @test3(i32 %x, i32 %y) {
; CHECK: @test3(i32 %x, i32 %y)
; CHECK: %add1 = add i32 %x, %y
; CHECK: %foo = add i32 %add1, %add1
%add1 = add nuw nsw i32 %x, %y
%add2 = add i32 %x, %y
%foo = add i32 %add1, %add2
ret i32 %foo
}
define i32 @test4(i32 %x, i32 %y) {
; CHECK: @test4(i32 %x, i32 %y)
; CHECK: %add1 = add nsw i32 %x, %y
; CHECK: %foo = add i32 %add1, %add1
%add1 = add nsw i32 %x, %y
%add2 = add nsw i32 %x, %y
%foo = add i32 %add1, %add2
ret i32 %foo
}
define i32 @test5(i32 %x, i32 %y) {
; CHECK: @test5(i32 %x, i32 %y)
; CHECK: %add1 = add i32 %x, %y
; CHECK: %foo = add i32 %add1, %add1
%add1 = add nuw i32 %x, %y
%add2 = add nsw i32 %x, %y
%foo = add i32 %add1, %add2
ret i32 %foo
}
define i32 @test6(i32 %x, i32 %y) {
; CHECK: @test6(i32 %x, i32 %y)
; CHECK: %add1 = add nsw i32 %x, %y
; CHECK: %foo = add i32 %add1, %add1
%add1 = add nuw nsw i32 %x, %y
%add2 = add nsw i32 %x, %y
%foo = add i32 %add1, %add2
ret i32 %foo
}
define i32 @test7(i32 %x, i32 %y) {
; CHECK: @test7(i32 %x, i32 %y)
; CHECK: %add1 = add i32 %x, %y
; CHECK-NOT: what_is_this
; CHECK: %foo = add i32 %add1, %add1
%add1 = add i32 %x, %y, !what_is_this !{}
%add2 = add i32 %x, %y
%foo = add i32 %add1, %add2
ret i32 %foo
}

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@ -0,0 +1,101 @@
; RUN: opt %s -basicaa -gvn -S -o - | FileCheck %s
define i32 @test1(i32* %p) {
; CHECK: @test1(i32* %p)
; CHECK: %a = load i32* %p, !range !0
; CHECK: %c = add i32 %a, %a
%a = load i32* %p, !range !0
%b = load i32* %p, !range !0
%c = add i32 %a, %b
ret i32 %c
}
define i32 @test2(i32* %p) {
; CHECK: @test2(i32* %p)
; CHECK: %a = load i32* %p
; CHECK-NOT: range
; CHECK: %c = add i32 %a, %a
%a = load i32* %p, !range !0
%b = load i32* %p
%c = add i32 %a, %b
ret i32 %c
}
define i32 @test3(i32* %p) {
; CHECK: @test3(i32* %p)
; CHECK: %a = load i32* %p, !range ![[DISJOINT_RANGE:[0-9]+]]
; CHECK: %c = add i32 %a, %a
%a = load i32* %p, !range !0
%b = load i32* %p, !range !1
%c = add i32 %a, %b
ret i32 %c
}
define i32 @test4(i32* %p) {
; CHECK: @test4(i32* %p)
; CHECK: %a = load i32* %p, !range ![[MERGED_RANGE:[0-9]+]]
; CHECK: %c = add i32 %a, %a
%a = load i32* %p, !range !0
%b = load i32* %p, !range !2
%c = add i32 %a, %b
ret i32 %c
}
define i32 @test5(i32* %p) {
; CHECK: @test5(i32* %p)
; CHECK: %a = load i32* %p, !range ![[MERGED_SIGNED_RANGE:[0-9]+]]
; CHECK: %c = add i32 %a, %a
%a = load i32* %p, !range !3
%b = load i32* %p, !range !4
%c = add i32 %a, %b
ret i32 %c
}
define i32 @test6(i32* %p) {
; CHECK: @test6(i32* %p)
; CHECK: %a = load i32* %p, !range ![[MERGED_TEST6:[0-9]+]]
; CHECK: %c = add i32 %a, %a
%a = load i32* %p, !range !5
%b = load i32* %p, !range !6
%c = add i32 %a, %b
ret i32 %c
}
define i32 @test7(i32* %p) {
; CHECK: @test7(i32* %p)
; CHECK: %a = load i32* %p, !range ![[MERGED_TEST7:[0-9]+]]
; CHECK: %c = add i32 %a, %a
%a = load i32* %p, !range !7
%b = load i32* %p, !range !8
%c = add i32 %a, %b
ret i32 %c
}
define i32 @test8(i32* %p) {
; CHECK: @test8(i32* %p)
; CHECK: %a = load i32* %p
; CHECK-NOT: range
; CHECK: %c = add i32 %a, %a
%a = load i32* %p, !range !9
%b = load i32* %p, !range !10
%c = add i32 %a, %b
ret i32 %c
}
; CHECK: ![[DISJOINT_RANGE]] = metadata !{i32 0, i32 2, i32 3, i32 5}
; CHECK: ![[MERGED_RANGE]] = metadata !{i32 0, i32 5}
; CHECK: ![[MERGED_SIGNED_RANGE]] = metadata !{i32 -3, i32 -2, i32 1, i32 2}
; CHECK: ![[MERGED_TEST6]] = metadata !{i32 10, i32 1}
; CHECK: ![[MERGED_TEST7]] = metadata !{i32 3, i32 4, i32 5, i32 2}
!0 = metadata !{i32 0, i32 2}
!1 = metadata !{i32 3, i32 5}
!2 = metadata !{i32 2, i32 5}
!3 = metadata !{i32 -3, i32 -2}
!4 = metadata !{i32 1, i32 2}
!5 = metadata !{i32 10, i32 1}
!6 = metadata !{i32 12, i32 13}
!7 = metadata !{i32 1, i32 2, i32 3, i32 4}
!8 = metadata !{i32 5, i32 1}
!9 = metadata !{i32 1, i32 5}
!10 = metadata !{i32 5, i32 1}

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@ -0,0 +1,81 @@
; RUN: opt %s -basicaa -gvn -S -o - | FileCheck %s
define i32 @test1(i8* %p, i8* %q) {
; CHECK: @test1(i8* %p, i8* %q)
; CHECK: call i32 @foo(i8* %p)
; CHECK-NOT: tbaa
; CHECK: %c = add i32 %a, %a
%a = call i32 @foo(i8* %p), !tbaa !0
%b = call i32 @foo(i8* %p)
%c = add i32 %a, %b
ret i32 %c
}
define i32 @test2(i8* %p, i8* %q) {
; CHECK: @test2(i8* %p, i8* %q)
; CHECK: call i32 @foo(i8* %p), !tbaa !0
; CHECK: %c = add i32 %a, %a
%a = call i32 @foo(i8* %p), !tbaa !0
%b = call i32 @foo(i8* %p), !tbaa !0
%c = add i32 %a, %b
ret i32 %c
}
define i32 @test3(i8* %p, i8* %q) {
; CHECK: @test3(i8* %p, i8* %q)
; CHECK: call i32 @foo(i8* %p), !tbaa !3
; CHECK: %c = add i32 %a, %a
%a = call i32 @foo(i8* %p), !tbaa !3
%b = call i32 @foo(i8* %p), !tbaa !3
%c = add i32 %a, %b
ret i32 %c
}
define i32 @test4(i8* %p, i8* %q) {
; CHECK: @test4(i8* %p, i8* %q)
; CHECK: call i32 @foo(i8* %p), !tbaa !1
; CHECK: %c = add i32 %a, %a
%a = call i32 @foo(i8* %p), !tbaa !1
%b = call i32 @foo(i8* %p), !tbaa !0
%c = add i32 %a, %b
ret i32 %c
}
define i32 @test5(i8* %p, i8* %q) {
; CHECK: @test5(i8* %p, i8* %q)
; CHECK: call i32 @foo(i8* %p), !tbaa !1
; CHECK: %c = add i32 %a, %a
%a = call i32 @foo(i8* %p), !tbaa !0
%b = call i32 @foo(i8* %p), !tbaa !1
%c = add i32 %a, %b
ret i32 %c
}
define i32 @test6(i8* %p, i8* %q) {
; CHECK: @test6(i8* %p, i8* %q)
; CHECK: call i32 @foo(i8* %p), !tbaa !1
; CHECK: %c = add i32 %a, %a
%a = call i32 @foo(i8* %p), !tbaa !0
%b = call i32 @foo(i8* %p), !tbaa !3
%c = add i32 %a, %b
ret i32 %c
}
define i32 @test7(i8* %p, i8* %q) {
; CHECK: @test7(i8* %p, i8* %q)
; CHECK: call i32 @foo(i8* %p)
; CHECK-NOT: tbaa
; CHECK: %c = add i32 %a, %a
%a = call i32 @foo(i8* %p), !tbaa !4
%b = call i32 @foo(i8* %p), !tbaa !3
%c = add i32 %a, %b
ret i32 %c
}
declare i32 @foo(i8*) readonly
!0 = metadata !{metadata !"C", metadata !1}
!1 = metadata !{metadata !"A", metadata !2}
!2 = metadata !{metadata !"tbaa root", null}
!3 = metadata !{metadata !"B", metadata !1}
!4 = metadata !{metadata !"another root", null}