[llvm-commits] [llvm] r159146 - in /llvm/trunk: lib/Transforms/InstCombine/InstructionCombining.cpp lib/Transforms/Scalar/SimplifyCFGPass.cpp lib/VMCore/Verifier.cpp test/Transforms/InstCombine/objsize-64.ll test/Transforms/SimplifyCFG/invoke.ll
Duncan Sands
baldrick at free.fr
Mon Jun 25 13:09:40 PDT 2012
Hi Nuno,
> improve optimization of invoke instructions:
> - simplifycfg: invoke undef/null -> unreachable
this part if OK.
> - instcombine: invoke new -> invoke expect(0, 0) (an arbitrary NOOP intrinsic; only done if the allocated memory is unused, of course)
What is this about? If you are saying that malloc is nounwind, why aren't you
marking it nounwind in SimplifyLibCalls.
In any case, by removing the restriction that you can't do invoke on an
intrinsic you are making a major (historically speaking change). It should
thus be done as part of a different commit, and accompanied with a bunch of
tests checking that codegen doesn't crash if you try to codegen code that
does invoke of an intrinsic.
Finally, doing thus funky intrinsic thing seems a bizarre approach to me,
there has to be a better way.
I think plenty of people made these remarks already, but I didn't notice
you answering those objections - maybe I just missed it?
Ciao, Duncan.
> - verifier: allow invoke of intrinsics (to make the previous step work)
>
> Added:
> llvm/trunk/test/Transforms/SimplifyCFG/invoke.ll
> Modified:
> llvm/trunk/lib/Transforms/InstCombine/InstructionCombining.cpp
> llvm/trunk/lib/Transforms/Scalar/SimplifyCFGPass.cpp
> llvm/trunk/lib/VMCore/Verifier.cpp
> llvm/trunk/test/Transforms/InstCombine/objsize-64.ll
>
> Modified: llvm/trunk/lib/Transforms/InstCombine/InstructionCombining.cpp
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/InstCombine/InstructionCombining.cpp?rev=159146&r1=159145&r2=159146&view=diff
> ==============================================================================
> --- llvm/trunk/lib/Transforms/InstCombine/InstructionCombining.cpp (original)
> +++ llvm/trunk/lib/Transforms/InstCombine/InstructionCombining.cpp Mon Jun 25 12:11:47 2012
> @@ -1169,7 +1169,14 @@
> }
>
> 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);
> }
>
> Modified: llvm/trunk/lib/Transforms/Scalar/SimplifyCFGPass.cpp
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/Scalar/SimplifyCFGPass.cpp?rev=159146&r1=159145&r2=159146&view=diff
> ==============================================================================
> --- llvm/trunk/lib/Transforms/Scalar/SimplifyCFGPass.cpp (original)
> +++ llvm/trunk/lib/Transforms/Scalar/SimplifyCFGPass.cpp Mon Jun 25 12:11:47 2012
> @@ -157,11 +157,16 @@
> }
>
> // 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)
>
> Modified: llvm/trunk/lib/VMCore/Verifier.cpp
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/VMCore/Verifier.cpp?rev=159146&r1=159145&r2=159146&view=diff
> ==============================================================================
> --- llvm/trunk/lib/VMCore/Verifier.cpp (original)
> +++ llvm/trunk/lib/VMCore/Verifier.cpp Mon Jun 25 12:11:47 2012
> @@ -1636,7 +1636,8 @@
> 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);
>
> Modified: llvm/trunk/test/Transforms/InstCombine/objsize-64.ll
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/InstCombine/objsize-64.ll?rev=159146&r1=159145&r2=159146&view=diff
> ==============================================================================
> --- llvm/trunk/test/Transforms/InstCombine/objsize-64.ll (original)
> +++ llvm/trunk/test/Transforms/InstCombine/objsize-64.ll Mon Jun 25 12:11:47 2012
> @@ -19,7 +19,7 @@
> ; 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
>
>
> Added: llvm/trunk/test/Transforms/SimplifyCFG/invoke.ll
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/SimplifyCFG/invoke.ll?rev=159146&view=auto
> ==============================================================================
> --- llvm/trunk/test/Transforms/SimplifyCFG/invoke.ll (added)
> +++ llvm/trunk/test/Transforms/SimplifyCFG/invoke.ll Mon Jun 25 12:11:47 2012
> @@ -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
> +}
>
>
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