maxjhandsome
/
llvm-project
forked from OSchip/llvm-project
1
0
Fork 0
Code Issues Pull Requests Packages Releases Wiki Activity

[SimplifyCFG] Teach removeUndefIntroducingPredecessor to preserve DomTree

This commit is contained in:
Roman Lebedev 2021-01-01 21:58:12 +03:00
parent 2461cdb417
commit b4429f3cdd
No known key found for this signature in database
GPG Key ID: 083C3EBB4A1689E0
6 changed files with 14 additions and 9 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

13
llvm/lib/Transforms/Utils/SimplifyCFG.cpp
View File

@ -6563,14 +6563,16 @@ static bool passingValueIsAlwaysUndefined(Value *V, Instruction *I) {
/// If BB has an incoming value that will always trigger undefined behavior
/// (eg. null pointer dereference), remove the branch leading here.
static bool removeUndefIntroducingPredecessor(BasicBlock *BB) {
static bool removeUndefIntroducingPredecessor(BasicBlock *BB,
DomTreeUpdater *DTU) {
for (PHINode &PHI : BB->phis())
for (unsigned i = 0, e = PHI.getNumIncomingValues(); i != e; ++i)
if (passingValueIsAlwaysUndefined(PHI.getIncomingValue(i), &PHI)) {
Instruction *T = PHI.getIncomingBlock(i)->getTerminator();
BasicBlock *Predecessor = PHI.getIncomingBlock(i);
Instruction *T = Predecessor->getTerminator();
IRBuilder<> Builder(T);
if (BranchInst *BI = dyn_cast<BranchInst>(T)) {
BB->removePredecessor(PHI.getIncomingBlock(i));
BB->removePredecessor(Predecessor);
// Turn uncoditional branches into unreachables and remove the dead
// destination from conditional branches.
if (BI->isUnconditional())
@ -6579,6 +6581,9 @@ static bool removeUndefIntroducingPredecessor(BasicBlock *BB) {
Builder.CreateBr(BI->getSuccessor(0) == BB ? BI->getSuccessor(1)
: BI->getSuccessor(0));
BI->eraseFromParent();
if (DTU)
DTU->applyUpdatesPermissive(
{{DominatorTree::Delete, Predecessor, BB}});
return true;
}
// TODO: SwitchInst.
@ -6611,7 +6616,7 @@ bool SimplifyCFGOpt::simplifyOnceImpl(BasicBlock *BB) {
Changed |= EliminateDuplicatePHINodes(BB);
// Check for and remove branches that will always cause undefined behavior.
Changed |= removeUndefIntroducingPredecessor(BB);
Changed |= removeUndefIntroducingPredecessor(BB, DTU);
// Merge basic blocks into their predecessor if there is only one distinct
// pred, and if there is only one distinct successor of the predecessor, and

2
llvm/test/CodeGen/Hexagon/misaligned_double_vector_store_not_fast.ll
View File

@ -1,4 +1,4 @@
; RUN: llc -march=hexagon -O3 -debug-only=isel 2>&1 -simplifycfg-require-and-preserve-domtree=0 < %s | FileCheck %s
; RUN: llc -march=hexagon -O3 -debug-only=isel 2>&1 -simplifycfg-require-and-preserve-domtree=1 < %s | FileCheck %s
; REQUIRES: asserts
; DAGCombiner converts the two vector stores to a double vector store,

2
llvm/test/CodeGen/Hexagon/swp-epilog-phi10.ll
View File

@ -1,4 +1,4 @@
; RUN: llc -march=hexagon -mcpu=hexagonv5 -simplifycfg-require-and-preserve-domtree=0 < %s
; RUN: llc -march=hexagon -mcpu=hexagonv5 -simplifycfg-require-and-preserve-domtree=1 < %s
; REQUIRES: asserts
define void @test(i8* noalias nocapture readonly %src, i32 %srcStride) local_unnamed_addr #0 {

2
llvm/test/CodeGen/Hexagon/swp-order-deps3.ll
View File

@ -1,4 +1,4 @@
; RUN: llc -march=hexagon -O2 -simplifycfg-require-and-preserve-domtree=0 < %s
; RUN: llc -march=hexagon -O2 -simplifycfg-require-and-preserve-domtree=1 < %s
; REQUIRES: asserts
; Function Attrs: noinline nounwind ssp

2
llvm/test/CodeGen/Hexagon/swp-reuse-phi-4.ll
View File

@ -1,4 +1,4 @@
; RUN: llc -march=hexagon -O2 -simplifycfg-require-and-preserve-domtree=0 < %s
; RUN: llc -march=hexagon -O2 -simplifycfg-require-and-preserve-domtree=1 < %s
; REQUIRES: asserts
; Test that we generate the correct Phi names in the epilog when we need

2
llvm/test/CodeGen/Thumb2/2009-08-04-CoalescerBug.ll
View File

@ -1,4 +1,4 @@
; RUN: llc -simplifycfg-require-and-preserve-domtree=0 < %s -mtriple=thumbv7-apple-darwin -mcpu=cortex-a8 -relocation-model=pic -frame-pointer=all
; RUN: llc -simplifycfg-require-and-preserve-domtree=1 < %s -mtriple=thumbv7-apple-darwin -mcpu=cortex-a8 -relocation-model=pic -frame-pointer=all
%0 = type { %struct.GAP } ; type %0
%1 = type { i16, i8, i8 } ; type %1