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commit 24b1a5b926832f68fa0a008b2484d4b44f58ee8e
Author: dim <dim@FreeBSD.org>
Date: Sat Sep 14 10:55:33 2019 +0000
Revert commit from upstream llvm trunk (by Hans Wennborg):
Re-commit r357452 (take 3): "SimplifyCFG
SinkCommonCodeFromPredecessors: Also sink function calls without used
results (PR41259)"
Third time's the charm.
This was reverted in r363220 due to being suspected of an internal
benchmark regression and a test failure, none of which turned out to
be caused by this.
As reported in https://bugs.llvm.org/show_bug.cgi?id=43269, this causes
UNREACHABLE errors when compiling if_malo_pci.c for arm and aarch64.
Notes:
svn path=/projects/clang900-import/; revision=352318
diff --git lib/Transforms/Utils/SimplifyCFG.cpp lib/Transforms/Utils/SimplifyCFG.cpp
index 11651d040dc0..6e2ef67408d9 100644
--- llvm/lib/Transforms/Utils/SimplifyCFG.cpp
+++ llvm/lib/Transforms/Utils/SimplifyCFG.cpp
@@ -1428,10 +1428,9 @@ static bool HoistThenElseCodeToIf(BranchInst *BI,
static bool canSinkInstructions(
ArrayRef<Instruction *> Insts,
DenseMap<Instruction *, SmallVector<Value *, 4>> &PHIOperands) {
- // Prune out obviously bad instructions to move. Each instruction must have
- // exactly zero or one use, and we check later that use is by a single, common
- // PHI instruction in the successor.
- bool HasUse = !Insts.front()->user_empty();
+ // Prune out obviously bad instructions to move. Any non-store instruction
+ // must have exactly one use, and we check later that use is by a single,
+ // common PHI instruction in the successor.
for (auto *I : Insts) {
// These instructions may change or break semantics if moved.
if (isa<PHINode>(I) || I->isEHPad() || isa<AllocaInst>(I) ||
@@ -1445,10 +1444,9 @@ static bool canSinkInstructions(
if (C->isInlineAsm())
return false;
- // Each instruction must have zero or one use.
- if (HasUse && !I->hasOneUse())
- return false;
- if (!HasUse && !I->user_empty())
+ // Everything must have only one use too, apart from stores which
+ // have no uses.
+ if (!isa<StoreInst>(I) && !I->hasOneUse())
return false;
}
@@ -1457,11 +1455,11 @@ static bool canSinkInstructions(
if (!I->isSameOperationAs(I0))
return false;
- // All instructions in Insts are known to be the same opcode. If they have a
- // use, check that the only user is a PHI or in the same block as the
- // instruction, because if a user is in the same block as an instruction we're
- // contemplating sinking, it must already be determined to be sinkable.
- if (HasUse) {
+ // All instructions in Insts are known to be the same opcode. If they aren't
+ // stores, check the only user of each is a PHI or in the same block as the
+ // instruction, because if a user is in the same block as an instruction
+ // we're contemplating sinking, it must already be determined to be sinkable.
+ if (!isa<StoreInst>(I0)) {
auto *PNUse = dyn_cast<PHINode>(*I0->user_begin());
auto *Succ = I0->getParent()->getTerminator()->getSuccessor(0);
if (!all_of(Insts, [&PNUse,&Succ](const Instruction *I) -> bool {
@@ -1539,7 +1537,7 @@ static bool sinkLastInstruction(ArrayRef<BasicBlock*> Blocks) {
// it is slightly over-aggressive - it gets confused by commutative instructions
// so double-check it here.
Instruction *I0 = Insts.front();
- if (!I0->user_empty()) {
+ if (!isa<StoreInst>(I0)) {
auto *PNUse = dyn_cast<PHINode>(*I0->user_begin());
if (!all_of(Insts, [&PNUse](const Instruction *I) -> bool {
auto *U = cast<Instruction>(*I->user_begin());
@@ -1597,10 +1595,11 @@ static bool sinkLastInstruction(ArrayRef<BasicBlock*> Blocks) {
I0->andIRFlags(I);
}
- if (!I0->user_empty()) {
+ if (!isa<StoreInst>(I0)) {
// canSinkLastInstruction checked that all instructions were used by
// one and only one PHI node. Find that now, RAUW it to our common
// instruction and nuke it.
+ assert(I0->hasOneUse());
auto *PN = cast<PHINode>(*I0->user_begin());
PN->replaceAllUsesWith(I0);
PN->eraseFromParent();
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