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[EarlyCSE] Make PhiToCheck in removeMSSA() a set. 

This way we end up not looking at PHI args already removed.
MemSSA now goes through the updater so we can prune
it to avoid having redundant MemoryPHI arguments, but that
doesn't quite work for the general case.

Discussed with Daniel Berlin, fixes PR33406.

llvm-svn: 305409
This commit is contained in:
Davide Italiano 2017-06-14 19:29:53 +00:00
parent dceb612eeb
commit 0dc4778067
2 changed files with 29 additions and 2 deletions
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5
llvm/lib/Transforms/Scalar/EarlyCSE.cpp
View File

@ -15,6 +15,7 @@
#include "llvm/Transforms/Scalar/EarlyCSE.h"
#include "llvm/ADT/Hashing.h"
#include "llvm/ADT/ScopedHashTable.h"
#include "llvm/ADT/SetVector.h"
#include "llvm/ADT/Statistic.h"
#include "llvm/Analysis/AssumptionCache.h"
#include "llvm/Analysis/GlobalsModRef.h"
@ -506,7 +507,7 @@ private:
if (MemoryAccess *MA = MSSA->getMemoryAccess(Inst)) {
// Optimize MemoryPhi nodes that may become redundant by having all the
// same input values once MA is removed.
SmallVector<MemoryPhi *, 4> PhisToCheck;
SmallSetVector<MemoryPhi *, 4> PhisToCheck;
SmallVector<MemoryAccess *, 8> WorkQueue;
WorkQueue.push_back(MA);
// Process MemoryPhi nodes in FIFO order using a ever-growing vector since
@ -517,7 +518,7 @@ private:
for (auto *U : WI->users())
if (MemoryPhi *MP = dyn_cast<MemoryPhi>(U))
PhisToCheck.push_back(MP);
PhisToCheck.insert(MP);
MSSAUpdater->removeMemoryAccess(WI);

26
llvm/test/Transforms/EarlyCSE/pr33406.ll Normal file
View File

@ -0,0 +1,26 @@
; RUN: opt -early-cse-memssa -S %s | FileCheck %s
; CHECK: define void @patatino() {
; CHECK: for.cond:
; CHECK-NEXT: br i1 true, label %if.end, label %for.inc
; CHECK: if.end:
; CHECK-NEXT: %tinkywinky = load i32, i32* @b
; CHECK-NEXT: br i1 true, label %for.inc, label %for.inc
; CHECK: for.inc:
; CHECK-NEXT: ret void
@b = external global i32
define void @patatino() {
for.cond:
br i1 true, label %if.end, label %for.inc
if.end:
%tinkywinky = load i32, i32* @b
store i32 %tinkywinky, i32* @b
br i1 true, label %for.inc, label %for.inc
for.inc:
ret void
}