Speculatively revert 112699 and 112702, they seem to be causing
self host errors on clang-x86-64.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@112719 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/DwarfEHPrepare.cpp b/lib/CodeGen/DwarfEHPrepare.cpp
index 550fd3e..2522d0b 100644
--- a/lib/CodeGen/DwarfEHPrepare.cpp
+++ b/lib/CodeGen/DwarfEHPrepare.cpp
@@ -25,12 +25,12 @@
#include "llvm/Support/CallSite.h"
#include "llvm/Target/TargetLowering.h"
#include "llvm/Transforms/Utils/BasicBlockUtils.h"
-#include "llvm/Transforms/Utils/SSAUpdater.h"
using namespace llvm;
STATISTIC(NumLandingPadsSplit, "Number of landing pads split");
STATISTIC(NumUnwindsLowered, "Number of unwind instructions lowered");
STATISTIC(NumExceptionValuesMoved, "Number of eh.exception calls moved");
+STATISTIC(NumStackTempsIntroduced, "Number of stack temporaries introduced");
namespace {
class DwarfEHPrepare : public FunctionPass {
@@ -62,11 +62,24 @@
typedef SmallPtrSet<BasicBlock*, 8> BBSet;
BBSet LandingPads;
+ // Stack temporary used to hold eh.exception values.
+ AllocaInst *ExceptionValueVar;
+
bool NormalizeLandingPads();
bool LowerUnwinds();
bool MoveExceptionValueCalls();
+ bool FinishStackTemporaries();
Instruction *CreateExceptionValueCall(BasicBlock *BB);
+ Instruction *CreateValueLoad(BasicBlock *BB);
+
+ /// CreateReadOfExceptionValue - Return the result of the eh.exception
+ /// intrinsic by calling the intrinsic if in a landing pad, or loading it
+ /// from the exception value variable otherwise.
+ Instruction *CreateReadOfExceptionValue(BasicBlock *BB) {
+ return LandingPads.count(BB) ?
+ CreateExceptionValueCall(BB) : CreateValueLoad(BB);
+ }
/// CleanupSelectors - Any remaining eh.selector intrinsic calls which still
/// use the "llvm.eh.catch.all.value" call need to convert to using its
@@ -104,7 +117,7 @@
virtual bool runOnFunction(Function &Fn);
- // getAnalysisUsage - We need the dominator tree for handling URoR.
+ // getAnalysisUsage - We need dominance frontiers for memory promotion.
virtual void getAnalysisUsage(AnalysisUsage &AU) const {
AU.addRequired<DominatorTree>();
AU.addPreserved<DominatorTree>();
@@ -504,7 +517,7 @@
// Create the call...
CallInst *CI = CallInst::Create(RewindFunction,
- CreateExceptionValueCall(TI->getParent()),
+ CreateReadOfExceptionValue(TI->getParent()),
"", TI);
CI->setCallingConv(TLI->getLibcallCallingConv(RTLIB::UNWIND_RESUME));
// ...followed by an UnreachableInst.
@@ -520,11 +533,9 @@
}
/// MoveExceptionValueCalls - Ensure that eh.exception is only ever called from
-/// landing pads by replacing calls outside of landing pads with direct use of
-/// a register holding the appropriate value; this requires adding calls inside
-/// all landing pads to initialize the register. Also, move eh.exception calls
-/// inside landing pads to the start of the landing pad (optional, but may make
-/// things simpler for later passes).
+/// landing pads by replacing calls outside of landing pads with loads from a
+/// stack temporary. Move eh.exception calls inside landing pads to the start
+/// of the landing pad (optional, but may make things simpler for later passes).
bool DwarfEHPrepare::MoveExceptionValueCalls() {
// If the eh.exception intrinsic is not declared in the module then there is
// nothing to do. Speed up compilation by checking for this common case.
@@ -534,87 +545,49 @@
bool Changed = false;
- // Move calls to eh.exception that are inside a landing pad to the start of
- // the landing pad.
- for (BBSet::const_iterator LI = LandingPads.begin(), LE = LandingPads.end();
- LI != LE; ++LI) {
- BasicBlock *LP = *LI;
- for (BasicBlock::iterator II = LP->getFirstNonPHIOrDbg(), IE = LP->end();
- II != IE;)
- if (EHExceptionInst *EI = dyn_cast<EHExceptionInst>(II++)) {
- // Found a call to eh.exception.
- if (!EI->use_empty()) {
- // If there is already a call to eh.exception at the start of the
- // landing pad, then get hold of it; otherwise create such a call.
- Value *CallAtStart = CreateExceptionValueCall(LP);
-
- // If the call was at the start of a landing pad then leave it alone.
- if (EI == CallAtStart)
- continue;
- EI->replaceAllUsesWith(CallAtStart);
+ for (Function::iterator BB = F->begin(), E = F->end(); BB != E; ++BB) {
+ for (BasicBlock::iterator II = BB->begin(), E = BB->end(); II != E;)
+ if (IntrinsicInst *CI = dyn_cast<IntrinsicInst>(II++))
+ if (CI->getIntrinsicID() == Intrinsic::eh_exception) {
+ if (!CI->use_empty()) {
+ Value *ExceptionValue = CreateReadOfExceptionValue(BB);
+ if (CI == ExceptionValue) {
+ // The call was at the start of a landing pad - leave it alone.
+ assert(LandingPads.count(BB) &&
+ "Created eh.exception call outside landing pad!");
+ continue;
+ }
+ CI->replaceAllUsesWith(ExceptionValue);
+ }
+ CI->eraseFromParent();
+ ++NumExceptionValuesMoved;
+ Changed = true;
}
- EI->eraseFromParent();
- ++NumExceptionValuesMoved;
- Changed = true;
- }
}
- // Look for calls to eh.exception that are not in a landing pad. If one is
- // found, then a register that holds the exception value will be created in
- // each landing pad, and the SSAUpdater will be used to compute the values
- // returned by eh.exception calls outside of landing pads.
- SSAUpdater SSA;
+ return Changed;
+}
- // Remember where we found the eh.exception call, to avoid rescanning earlier
- // basic blocks which we already know contain no eh.exception calls.
- bool FoundCallOutsideLandingPad = false;
- Function::iterator BB = F->begin();
- for (Function::iterator BE = F->end(); BB != BE; ++BB) {
- // Skip over landing pads.
- if (LandingPads.count(BB))
- continue;
+/// FinishStackTemporaries - If we introduced a stack variable to hold the
+/// exception value then initialize it in each landing pad.
+bool DwarfEHPrepare::FinishStackTemporaries() {
+ if (!ExceptionValueVar)
+ // Nothing to do.
+ return false;
- for (BasicBlock::iterator II = BB->getFirstNonPHIOrDbg(), IE = BB->end();
- II != IE; ++II)
- if (isa<EHExceptionInst>(II)) {
- SSA.Initialize(II->getType(), II->getName());
- FoundCallOutsideLandingPad = true;
- break;
- }
+ bool Changed = false;
- if (FoundCallOutsideLandingPad)
- break;
- }
-
- // If all calls to eh.exception are in landing pads then we are done.
- if (!FoundCallOutsideLandingPad)
- return Changed;
-
- // Add a call to eh.exception at the start of each landing pad, and tell the
- // SSAUpdater that this is the value produced by the landing pad.
+ // Make sure that there is a store of the exception value at the start of
+ // each landing pad.
for (BBSet::iterator LI = LandingPads.begin(), LE = LandingPads.end();
- LI != LE; ++LI)
- SSA.AddAvailableValue(*LI, CreateExceptionValueCall(*LI));
-
- // Now turn all calls to eh.exception that are not in a landing pad into a use
- // of the appropriate register.
- for (Function::iterator BE = F->end(); BB != BE; ++BB) {
- // Skip over landing pads.
- if (LandingPads.count(BB))
- continue;
-
- for (BasicBlock::iterator II = BB->getFirstNonPHIOrDbg(), IE = BB->end();
- II != IE;)
- if (EHExceptionInst *EI = dyn_cast<EHExceptionInst>(II++)) {
- // Found a call to eh.exception, replace it with the value from any
- // upstream landing pad(s).
- EI->replaceAllUsesWith(SSA.GetValueAtEndOfBlock(BB));
- EI->eraseFromParent();
- ++NumExceptionValuesMoved;
- }
+ LI != LE; ++LI) {
+ Instruction *ExceptionValue = CreateReadOfExceptionValue(*LI);
+ Instruction *Store = new StoreInst(ExceptionValue, ExceptionValueVar);
+ Store->insertAfter(ExceptionValue);
+ Changed = true;
}
- return true;
+ return Changed;
}
/// CreateExceptionValueCall - Insert a call to the eh.exception intrinsic at
@@ -637,11 +610,35 @@
return CallInst::Create(ExceptionValueIntrinsic, "eh.value.call", Start);
}
+/// CreateValueLoad - Insert a load of the exception value stack variable
+/// (creating it if necessary) at the start of the basic block (unless
+/// there already is a load, in which case the existing load is returned).
+Instruction *DwarfEHPrepare::CreateValueLoad(BasicBlock *BB) {
+ Instruction *Start = BB->getFirstNonPHIOrDbg();
+ // Is this a load of the exception temporary?
+ if (ExceptionValueVar)
+ if (LoadInst* LI = dyn_cast<LoadInst>(Start))
+ if (LI->getPointerOperand() == ExceptionValueVar)
+ // Reuse the existing load.
+ return Start;
+
+ // Create the temporary if we didn't already.
+ if (!ExceptionValueVar) {
+ ExceptionValueVar = new AllocaInst(PointerType::getUnqual(
+ Type::getInt8Ty(BB->getContext())), "eh.value", F->begin()->begin());
+ ++NumStackTempsIntroduced;
+ }
+
+ // Load the value.
+ return new LoadInst(ExceptionValueVar, "eh.value.load", Start);
+}
+
bool DwarfEHPrepare::runOnFunction(Function &Fn) {
bool Changed = false;
// Initialize internal state.
DT = &getAnalysis<DominatorTree>();
+ ExceptionValueVar = 0;
F = &Fn;
// Ensure that only unwind edges end at landing pads (a landing pad is a
@@ -656,6 +653,11 @@
// Move eh.exception calls to landing pads.
Changed |= MoveExceptionValueCalls();
+ // Initialize any stack temporaries we introduced.
+ Changed |= FinishStackTemporaries();
+
+ // TODO: Turn any stack temporaries into registers if possible.
+
Changed |= HandleURoRInvokes();
LandingPads.clear();