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improve optimization of invoke instructions:

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- simplifycfg:  invoke undef/null -> unreachable
 - instcombine:  invoke new  -> invoke expect(0, 0)  (an arbitrary NOOP intrinsic;  only done if the allocated memory is unused, of course)
 - verifier:  allow invoke of intrinsics  (to make the previous step work)

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@159146 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Nuno Lopes 2012-06-25 17:11:47 +00:00
parent e8742d084c
commit 3769fe149b
5 changed files with 63 additions and 5 deletions
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9
lib/Transforms/InstCombine/InstructionCombining.cpp
View File

@ -1169,7 +1169,14 @@ Instruction *InstCombiner::visitMalloc(Instruction &MI) {
}
if (InvokeInst *II = dyn_cast<InvokeInst>(&MI)) {
BranchInst::Create(II->getNormalDest(), II->getParent());
// Replace invoke with a NOOP intrinsic to maintain the original CFG
Module *M = II->getParent()->getParent()->getParent();
IntegerType *Ty = IntegerType::get(II->getContext(), 8);
ConstantInt *CI = ConstantInt::get(Ty, 0);
Value *Args[] = {CI, CI};
Function *F = Intrinsic::getDeclaration(M, Intrinsic::expect, Ty);
InvokeInst::Create(F, II->getNormalDest(), II->getUnwindDest(), Args,
"dummy", II->getParent());
}
return EraseInstFromFunction(MI);
}

9
lib/Transforms/Scalar/SimplifyCFGPass.cpp
View File

@ -157,11 +157,16 @@ static bool MarkAliveBlocks(BasicBlock *BB,
}
// Turn invokes that call 'nounwind' functions into ordinary calls.
if (InvokeInst *II = dyn_cast<InvokeInst>(BB->getTerminator()))
if (II->doesNotThrow()) {
if (InvokeInst *II = dyn_cast<InvokeInst>(BB->getTerminator())) {
Value *Callee = II->getCalledValue();
if (isa<ConstantPointerNull>(Callee) || isa<UndefValue>(Callee)) {
ChangeToUnreachable(II, true);
Changed = true;
} else if (II->doesNotThrow()) {
ChangeToCall(II);
Changed = true;
}
}
Changed |= ConstantFoldTerminator(BB, true);
for (succ_iterator SI = succ_begin(BB), SE = succ_end(BB); SI != SE; ++SI)

3
lib/VMCore/Verifier.cpp
View File

@ -1636,7 +1636,8 @@ void Verifier::visitInstruction(Instruction &I) {
if (Function *F = dyn_cast<Function>(I.getOperand(i))) {
// Check to make sure that the "address of" an intrinsic function is never
// taken.
Assert1(!F->isIntrinsic() || (i + 1 == e && isa<CallInst>(I)),
CallSite CS(&I);
Assert1(!F->isIntrinsic() || (CS && i == (CS.isCall() ? e-1 : 2)),
"Cannot take the address of an intrinsic!", &I);
Assert1(F->getParent() == Mod, "Referencing function in another module!",
&I);

2
test/Transforms/InstCombine/objsize-64.ll
View File

@ -19,7 +19,7 @@ define i64 @f1() {
; CHECK: @f2
define i64 @f2() nounwind uwtable ssp {
entry:
; CHECK: br label
; CHECK: invoke i8 @llvm.expect.i8(i8 0, i8 0)
%call = invoke noalias i8* @_Znwm(i64 13)
to label %invoke.cont unwind label %lpad

45
test/Transforms/SimplifyCFG/invoke.ll Normal file
View File

@ -0,0 +1,45 @@
; RUN: opt < %s -simplifycfg -S | FileCheck %s
target datalayout = "e-p:64:64:64-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:64:64-f32:32:32-f64:64:64-v64:64:64-v128:128:128-a0:0:64-s0:64:64-f80:128:128-n8:16:32:64-S128"
declare i32 @__gxx_personality_v0(...)
declare void @__cxa_call_unexpected(i8*)
declare i64 @llvm.objectsize.i64(i8*, i1) nounwind readonly
; CHECK: @f1
define i8* @f1() nounwind uwtable ssp {
entry:
; CHECK: call void @llvm.trap()
; CHECK: unreachable
%call = invoke noalias i8* undef()
to label %invoke.cont unwind label %lpad
invoke.cont:
ret i8* %call
lpad:
%0 = landingpad { i8*, i32 } personality i8* bitcast (i32 (...)* @__gxx_personality_v0 to i8*)
filter [0 x i8*] zeroinitializer
%1 = extractvalue { i8*, i32 } %0, 0
tail call void @__cxa_call_unexpected(i8* %1) noreturn nounwind
unreachable
}
; CHECK: @f2
define i8* @f2() nounwind uwtable ssp {
entry:
; CHECK: call void @llvm.trap()
; CHECK: unreachable
%call = invoke noalias i8* null()
to label %invoke.cont unwind label %lpad
invoke.cont:
ret i8* %call
lpad:
%0 = landingpad { i8*, i32 } personality i8* bitcast (i32 (...)* @__gxx_personality_v0 to i8*)
filter [0 x i8*] zeroinitializer
%1 = extractvalue { i8*, i32 } %0, 0
tail call void @__cxa_call_unexpected(i8* %1) noreturn nounwind
unreachable
}