73fd0eb88d
This is a copy of llvm15 at 79aeb739c5.
Copying it unmodifed makes it easy to diff to the source.
Sponsored by: DARPA
94 lines
4.1 KiB
Plaintext
94 lines
4.1 KiB
Plaintext
commit 24b1a5b926832f68fa0a008b2484d4b44f58ee8e
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Author: dim <dim@FreeBSD.org>
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Date: Sat Sep 14 10:55:33 2019 +0000
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Revert commit from upstream llvm trunk (by Hans Wennborg):
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Re-commit r357452 (take 3): "SimplifyCFG
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SinkCommonCodeFromPredecessors: Also sink function calls without used
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results (PR41259)"
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Third time's the charm.
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This was reverted in r363220 due to being suspected of an internal
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benchmark regression and a test failure, none of which turned out to
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be caused by this.
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As reported in https://bugs.llvm.org/show_bug.cgi?id=43269, this causes
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UNREACHABLE errors when compiling if_malo_pci.c for arm and aarch64.
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Notes:
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svn path=/projects/clang900-import/; revision=352318
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diff --git lib/Transforms/Utils/SimplifyCFG.cpp lib/Transforms/Utils/SimplifyCFG.cpp
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index 11651d040dc0..6e2ef67408d9 100644
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--- llvm/lib/Transforms/Utils/SimplifyCFG.cpp
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+++ llvm/lib/Transforms/Utils/SimplifyCFG.cpp
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@@ -1428,10 +1428,9 @@ static bool HoistThenElseCodeToIf(BranchInst *BI,
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static bool canSinkInstructions(
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ArrayRef<Instruction *> Insts,
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DenseMap<Instruction *, SmallVector<Value *, 4>> &PHIOperands) {
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- // Prune out obviously bad instructions to move. Each instruction must have
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- // exactly zero or one use, and we check later that use is by a single, common
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- // PHI instruction in the successor.
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- bool HasUse = !Insts.front()->user_empty();
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+ // Prune out obviously bad instructions to move. Any non-store instruction
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+ // must have exactly one use, and we check later that use is by a single,
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+ // common PHI instruction in the successor.
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for (auto *I : Insts) {
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// These instructions may change or break semantics if moved.
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if (isa<PHINode>(I) || I->isEHPad() || isa<AllocaInst>(I) ||
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@@ -1445,10 +1444,9 @@ static bool canSinkInstructions(
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if (C->isInlineAsm())
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return false;
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- // Each instruction must have zero or one use.
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- if (HasUse && !I->hasOneUse())
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- return false;
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- if (!HasUse && !I->user_empty())
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+ // Everything must have only one use too, apart from stores which
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+ // have no uses.
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+ if (!isa<StoreInst>(I) && !I->hasOneUse())
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return false;
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}
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@@ -1457,11 +1455,11 @@ static bool canSinkInstructions(
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if (!I->isSameOperationAs(I0))
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return false;
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- // All instructions in Insts are known to be the same opcode. If they have a
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- // use, check that the only user is a PHI or in the same block as the
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- // instruction, because if a user is in the same block as an instruction we're
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- // contemplating sinking, it must already be determined to be sinkable.
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- if (HasUse) {
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+ // All instructions in Insts are known to be the same opcode. If they aren't
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+ // stores, check the only user of each is a PHI or in the same block as the
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+ // instruction, because if a user is in the same block as an instruction
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+ // we're contemplating sinking, it must already be determined to be sinkable.
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+ if (!isa<StoreInst>(I0)) {
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auto *PNUse = dyn_cast<PHINode>(*I0->user_begin());
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auto *Succ = I0->getParent()->getTerminator()->getSuccessor(0);
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if (!all_of(Insts, [&PNUse,&Succ](const Instruction *I) -> bool {
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@@ -1539,7 +1537,7 @@ static bool sinkLastInstruction(ArrayRef<BasicBlock*> Blocks) {
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// it is slightly over-aggressive - it gets confused by commutative instructions
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// so double-check it here.
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Instruction *I0 = Insts.front();
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- if (!I0->user_empty()) {
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+ if (!isa<StoreInst>(I0)) {
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auto *PNUse = dyn_cast<PHINode>(*I0->user_begin());
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if (!all_of(Insts, [&PNUse](const Instruction *I) -> bool {
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auto *U = cast<Instruction>(*I->user_begin());
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@@ -1597,10 +1595,11 @@ static bool sinkLastInstruction(ArrayRef<BasicBlock*> Blocks) {
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I0->andIRFlags(I);
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}
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- if (!I0->user_empty()) {
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+ if (!isa<StoreInst>(I0)) {
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// canSinkLastInstruction checked that all instructions were used by
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// one and only one PHI node. Find that now, RAUW it to our common
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// instruction and nuke it.
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+ assert(I0->hasOneUse());
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auto *PN = cast<PHINode>(*I0->user_begin());
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PN->replaceAllUsesWith(I0);
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PN->eraseFromParent();
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