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Record landing pads with a SmallSetVector to avoid multiple entries. 

There may be many invokes that share one landing pad, and the previous code
would record the landing pad once for each invoke.  Besides the wasted
effort, a pair of volatile loads gets inserted every time the landing pad is
processed.  The rest of the code can get optimized away when a landing pad
is processed repeatedly, but the volatile loads remain, resulting in code like:

LBB35_18:
Ltmp483:
        ldr     r2, [r7, #-72]
        ldr     r2, [r7, #-68]
        ldr     r2, [r7, #-72]
        ldr     r2, [r7, #-68]
        ldr     r2, [r7, #-72]
        ldr     r2, [r7, #-68]
        ldr     r2, [r7, #-72]
        ldr     r2, [r7, #-68]
        ldr     r2, [r7, #-72]
        ldr     r2, [r7, #-68]
        ldr     r2, [r7, #-72]
        ldr     r2, [r7, #-68]
        ldr     r2, [r7, #-72]
        ldr     r2, [r7, #-68]
        ldr     r2, [r7, #-72]
        ldr     r2, [r7, #-68]
        ldr     r4, [r7, #-72]
        ldr     r2, [r7, #-68]

llvm-svn: 144787
This commit is contained in:
Bob Wilson 2011-11-16 07:57:21 +00:00
parent 2139c52d33
commit cca9aa58ca
1 changed files with 5 additions and 3 deletions
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8
llvm/lib/CodeGen/SjLjEHPrepare.cpp
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@ -30,6 +30,7 @@
#include "llvm/Support/Debug.h"
#include "llvm/Support/IRBuilder.h"
#include "llvm/ADT/DenseMap.h"
#include "llvm/ADT/SetVector.h"
#include "llvm/ADT/SmallPtrSet.h"
#include "llvm/ADT/SmallVector.h"
#include "llvm/ADT/Statistic.h"
@ -364,13 +365,13 @@ void SjLjEHPass::lowerAcrossUnwindEdges(Function &F,
bool SjLjEHPass::setupEntryBlockAndCallSites(Function &F) {
SmallVector<ReturnInst*, 16> Returns;
SmallVector<InvokeInst*, 16> Invokes;
SmallVector<LandingPadInst*, 16> LPads;
SmallSetVector<LandingPadInst*, 16> LPads;
// Look through the terminators of the basic blocks to find invokes.
for (Function::iterator BB = F.begin(), E = F.end(); BB != E; ++BB)
if (InvokeInst *II = dyn_cast<InvokeInst>(BB->getTerminator())) {
Invokes.push_back(II);
LPads.push_back(II->getUnwindDest()->getLandingPadInst());
LPads.insert(II->getUnwindDest()->getLandingPadInst());
} else if (ReturnInst *RI = dyn_cast<ReturnInst>(BB->getTerminator())) {
Returns.push_back(RI);
}
@ -382,7 +383,8 @@ bool SjLjEHPass::setupEntryBlockAndCallSites(Function &F) {
lowerIncomingArguments(F);
lowerAcrossUnwindEdges(F, Invokes);
Value *FuncCtx = setupFunctionContext(F, LPads);
Value *FuncCtx =
setupFunctionContext(F, makeArrayRef(LPads.begin(), LPads.end()));
BasicBlock *EntryBB = F.begin();
Type *Int32Ty = Type::getInt32Ty(F.getContext());