RPCS3/llvm-mirror
1
0
Fork 0
mirror of https://github.com/RPCS3/llvm-mirror.git synced 2025-01-31 20:51:52 +01:00
Code Issues Projects Releases Wiki Activity

Teach CorrelatedValuePropagation to mark adds as no wrap

Browse Source 
This is a resubmission of previously reverted r277592. It was hitting overly strong assertion in getConstantRange which was relaxed in r278217.

Use LVI to prove that adds do not wrap. The change is motivated by https://llvm.org/bugs/show_bug.cgi?id=28620 bug and it's the first step to fix that problem.

Reviewed By: sanjoy

Differential Revision: http://reviews.llvm.org/D23059

llvm-svn: 278220
This commit is contained in:
Artur Pilipenko 2016-08-10 13:08:34 +00:00
parent c0a2a41fc2
commit 062c0daef0
2 changed files with 148 additions and 0 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

57
lib/Transforms/Scalar/CorrelatedValuePropagation.cpp
View File

@ -18,6 +18,7 @@
#include "llvm/Analysis/InstructionSimplify.h"
#include "llvm/Analysis/LazyValueInfo.h"
#include "llvm/IR/CFG.h"
#include "llvm/IR/ConstantRange.h"
#include "llvm/IR/Constants.h"
#include "llvm/IR/Function.h"
#include "llvm/IR/Instructions.h"
@ -381,6 +382,59 @@ static bool processSDiv(BinaryOperator *SDI, LazyValueInfo *LVI) {
return true;
}
static bool processAdd(BinaryOperator *AddOp, LazyValueInfo *LVI) {
typedef OverflowingBinaryOperator OBO;
if (AddOp->getType()->isVectorTy() || hasLocalDefs(AddOp))
return false;
bool NSW = AddOp->hasNoSignedWrap();
bool NUW = AddOp->hasNoUnsignedWrap();
if (NSW && NUW)
return false;
BasicBlock *BB = AddOp->getParent();
Value *LHS = AddOp->getOperand(0);
Value *RHS = AddOp->getOperand(1);
ConstantRange LRange = LVI->getConstantRange(LHS, BB, AddOp);
// Initialize RRange only if we need it. If we know that guaranteed no wrap
// range for the given LHS range is empty don't spend time calculating the
// range for the RHS.
Optional<ConstantRange> RRange;
auto LazyRRange = [&] () {
if (!RRange)
RRange = LVI->getConstantRange(RHS, BB, AddOp);
return RRange.getValue();
};
bool Changed = false;
if (!NUW) {
ConstantRange NUWRange =
LRange.makeGuaranteedNoWrapRegion(BinaryOperator::Add, LRange,
OBO::NoUnsignedWrap);
if (!NUWRange.isEmptySet()) {
bool NewNUW = NUWRange.contains(LazyRRange());
AddOp->setHasNoUnsignedWrap(NewNUW);
Changed |= NewNUW;
}
}
if (!NSW) {
ConstantRange NSWRange =
LRange.makeGuaranteedNoWrapRegion(BinaryOperator::Add, LRange,
OBO::NoSignedWrap);
if (!NSWRange.isEmptySet()) {
bool NewNSW = NSWRange.contains(LazyRRange());
AddOp->setHasNoSignedWrap(NewNSW);
Changed |= NewNSW;
}
}
return Changed;
}
static Constant *getConstantAt(Value *V, Instruction *At, LazyValueInfo *LVI) {
if (Constant *C = LVI->getConstant(V, At->getParent(), At))
return C;
@ -436,6 +490,9 @@ static bool runImpl(Function &F, LazyValueInfo *LVI) {
case Instruction::SDiv:
BBChanged |= processSDiv(cast<BinaryOperator>(II), LVI);
break;
case Instruction::Add:
BBChanged |= processAdd(cast<BinaryOperator>(II), LVI);
break;
}
}

91
test/Transforms/CorrelatedValuePropagation/add.ll Normal file
View File

@ -0,0 +1,91 @@
; RUN: opt < %s -correlated-propagation -S | FileCheck %s
; CHECK-LABEL: @test0(
define void @test0(i32 %a) {
entry:
%cmp = icmp slt i32 %a, 100
br i1 %cmp, label %bb, label %exit
bb:
; CHECK: %add = add nsw i32 %a, 1
%add = add i32 %a, 1
br label %exit
exit:
ret void
}
; CHECK-LABEL: @test1(
define void @test1(i32 %a) {
entry:
%cmp = icmp ult i32 %a, 100
br i1 %cmp, label %bb, label %exit
bb:
; CHECK: %add = add nuw nsw i32 %a, 1
%add = add i32 %a, 1
br label %exit
exit:
ret void
}
; CHECK-LABEL: @test2(
define void @test2(i32 %a) {
entry:
%cmp = icmp ult i32 %a, -1
br i1 %cmp, label %bb, label %exit
bb:
; CHECK: %add = add nuw i32 %a, 1
%add = add i32 %a, 1
br label %exit
exit:
ret void
}
; CHECK-LABEL: @test3(
define void @test3(i32 %a) {
entry:
%cmp = icmp ule i32 %a, -1
br i1 %cmp, label %bb, label %exit
bb:
; CHECK: %add = add i32 %a, 1
%add = add i32 %a, 1
br label %exit
exit:
ret void
}
; CHECK-LABEL: @test4(
define void @test4(i32 %a) {
entry:
%cmp = icmp slt i32 %a, 2147483647
br i1 %cmp, label %bb, label %exit
bb:
; CHECK: %add = add nsw i32 %a, 1
%add = add i32 %a, 1
br label %exit
exit:
ret void
}
; CHECK-LABEL: @test5(
define void @test5(i32 %a) {
entry:
%cmp = icmp sle i32 %a, 2147483647
br i1 %cmp, label %bb, label %exit
bb:
; CHECK: %add = add i32 %a, 1
%add = add i32 %a, 1
br label %exit
exit:
ret void
}