[AggressiveInstCombine] Make TruncCombine class ignore unreachable basic blocks.
Because dead code may contain non-standard IR that causes infinite looping or crashes in underlying analysis.
See PR36134 for more details.
Differential Revision: https://reviews.llvm.org/D42683
llvm-svn: 323862
diff --git a/llvm/lib/Transforms/AggressiveInstCombine/AggressiveInstCombine.cpp b/llvm/lib/Transforms/AggressiveInstCombine/AggressiveInstCombine.cpp
index b7364d2..18432c0 100644
--- a/llvm/lib/Transforms/AggressiveInstCombine/AggressiveInstCombine.cpp
+++ b/llvm/lib/Transforms/AggressiveInstCombine/AggressiveInstCombine.cpp
@@ -20,6 +20,7 @@
#include "llvm/Analysis/GlobalsModRef.h"
#include "llvm/Analysis/TargetLibraryInfo.h"
#include "llvm/IR/DataLayout.h"
+#include "llvm/IR/Dominators.h"
#include "llvm/Pass.h"
#include "llvm/Transforms/Scalar.h"
using namespace llvm;
@@ -55,20 +56,23 @@
void AggressiveInstCombinerLegacyPass::getAnalysisUsage(
AnalysisUsage &AU) const {
AU.setPreservesCFG();
+ AU.addRequired<DominatorTreeWrapperPass>();
AU.addRequired<TargetLibraryInfoWrapperPass>();
AU.addPreserved<AAResultsWrapperPass>();
AU.addPreserved<BasicAAWrapperPass>();
+ AU.addPreserved<DominatorTreeWrapperPass>();
AU.addPreserved<GlobalsAAWrapperPass>();
}
bool AggressiveInstCombinerLegacyPass::runOnFunction(Function &F) {
+ auto &DT = getAnalysis<DominatorTreeWrapperPass>().getDomTree();
auto &TLI = getAnalysis<TargetLibraryInfoWrapperPass>().getTLI();
auto &DL = F.getParent()->getDataLayout();
bool MadeIRChange = false;
// Handle TruncInst patterns
- TruncInstCombine TIC(TLI, DL);
+ TruncInstCombine TIC(TLI, DL, DT);
MadeIRChange |= TIC.run(F);
// TODO: add more patterns to handle...
@@ -78,12 +82,13 @@
PreservedAnalyses AggressiveInstCombinePass::run(Function &F,
FunctionAnalysisManager &AM) {
+ auto &DT = AM.getResult<DominatorTreeAnalysis>(F);
auto &TLI = AM.getResult<TargetLibraryAnalysis>(F);
auto &DL = F.getParent()->getDataLayout();
bool MadeIRChange = false;
// Handle TruncInst patterns
- TruncInstCombine TIC(TLI, DL);
+ TruncInstCombine TIC(TLI, DL, DT);
MadeIRChange |= TIC.run(F);
if (!MadeIRChange)
// No changes, all analyses are preserved.
@@ -101,6 +106,7 @@
INITIALIZE_PASS_BEGIN(AggressiveInstCombinerLegacyPass,
"aggressive-instcombine",
"Combine pattern based expressions", false, false)
+INITIALIZE_PASS_DEPENDENCY(DominatorTreeWrapperPass)
INITIALIZE_PASS_DEPENDENCY(TargetLibraryInfoWrapperPass)
INITIALIZE_PASS_END(AggressiveInstCombinerLegacyPass, "aggressive-instcombine",
"Combine pattern based expressions", false, false)
diff --git a/llvm/lib/Transforms/AggressiveInstCombine/AggressiveInstCombineInternal.h b/llvm/lib/Transforms/AggressiveInstCombine/AggressiveInstCombineInternal.h
index 63255dd..d4655cf 100644
--- a/llvm/lib/Transforms/AggressiveInstCombine/AggressiveInstCombineInternal.h
+++ b/llvm/lib/Transforms/AggressiveInstCombine/AggressiveInstCombineInternal.h
@@ -45,11 +45,13 @@
namespace llvm {
class DataLayout;
+ class DominatorTree;
class TargetLibraryInfo;
class TruncInstCombine {
TargetLibraryInfo &TLI;
const DataLayout &DL;
+ const DominatorTree &DT;
/// List of all TruncInst instructions to be processed.
SmallVector<TruncInst *, 4> Worklist;
@@ -73,8 +75,9 @@
MapVector<Instruction *, Info> InstInfoMap;
public:
- TruncInstCombine(TargetLibraryInfo &TLI, const DataLayout &DL)
- : TLI(TLI), DL(DL), CurrentTruncInst(nullptr) {}
+ TruncInstCombine(TargetLibraryInfo &TLI, const DataLayout &DL,
+ const DominatorTree &DT)
+ : TLI(TLI), DL(DL), DT(DT), CurrentTruncInst(nullptr) {}
/// Perform TruncInst pattern optimization on given function.
bool run(Function &F);
diff --git a/llvm/lib/Transforms/AggressiveInstCombine/TruncInstCombine.cpp b/llvm/lib/Transforms/AggressiveInstCombine/TruncInstCombine.cpp
index deb0979..0378ea7 100644
--- a/llvm/lib/Transforms/AggressiveInstCombine/TruncInstCombine.cpp
+++ b/llvm/lib/Transforms/AggressiveInstCombine/TruncInstCombine.cpp
@@ -31,6 +31,7 @@
#include "llvm/Analysis/ConstantFolding.h"
#include "llvm/Analysis/TargetLibraryInfo.h"
#include "llvm/IR/DataLayout.h"
+#include "llvm/IR/Dominators.h"
#include "llvm/IR/IRBuilder.h"
using namespace llvm;
@@ -380,10 +381,14 @@
bool MadeIRChange = false;
// Collect all TruncInst in the function into the Worklist for evaluating.
- for (auto &BB : F)
+ for (auto &BB : F) {
+ // Ignore unreachable basic block.
+ if (!DT.isReachableFromEntry(&BB))
+ continue;
for (auto &I : BB)
if (auto *CI = dyn_cast<TruncInst>(&I))
Worklist.push_back(CI);
+ }
// Process all TruncInst in the Worklist, for each instruction:
// 1. Check if it dominates an eligible expression dag to be reduced.