[llvm] eccfa35 - Fix lifetime call in landingpad blocking Simplifycfg pass

[Roman Lebedev via llvm-commits]

This likely should ideally also look past new attribute
bundles/ephemeral values?

On Thu, Apr 9, 2020 at 11:07 PM Reid Kleckner via llvm-commits
<llvm-commits at lists.llvm.org> wrote:
>
>
> Author: Zequan Wu
> Date: 2020-04-09T13:07:32-07:00
> New Revision: eccfa35d53fbc78b09df6b4e58905e9d1d4c1c9a
>
> URL: https://github.com/llvm/llvm-project/commit/eccfa35d53fbc78b09df6b4e58905e9d1d4c1c9a
> DIFF: https://github.com/llvm/llvm-project/commit/eccfa35d53fbc78b09df6b4e58905e9d1d4c1c9a.diff
>
> LOG: Fix lifetime call in landingpad blocking Simplifycfg pass
>
> Fix lifetime call in landingpad blocks simplifycfg from removing the
> landingpad.
>
> Reviewed By: rnk
>
> Differential Revision: https://reviews.llvm.org/D77188
>
> Added:
>     llvm/test/Transforms/SimplifyCFG/lifetime-landingpad.ll
>
> Modified:
>     llvm/lib/Transforms/Utils/SimplifyCFG.cpp
>
> Removed:
>
>
>
> ################################################################################
> diff  --git a/llvm/lib/Transforms/Utils/SimplifyCFG.cpp b/llvm/lib/Transforms/Utils/SimplifyCFG.cpp
> index 9a39df4c35f8..263a0550a4dc 100644
> --- a/llvm/lib/Transforms/Utils/SimplifyCFG.cpp
> +++ b/llvm/lib/Transforms/Utils/SimplifyCFG.cpp
> @@ -3962,6 +3962,28 @@ bool SimplifyCFGOpt::simplifyCommonResume(ResumeInst *RI) {
>    return !TrivialUnwindBlocks.empty();
>  }
>
> +// Check if cleanup block is empty
> +static bool isCleanupBlockEmpty(Instruction *Inst, Instruction *RI) {
> +  BasicBlock::iterator I = Inst->getIterator(), E = RI->getIterator();
> +  while (++I != E) {
> +    auto *II = dyn_cast<IntrinsicInst>(I);
> +    if (!II)
> +      return false;
> +
> +    Intrinsic::ID IntrinsicID = II->getIntrinsicID();
> +    switch (IntrinsicID) {
> +    case Intrinsic::dbg_declare:
> +    case Intrinsic::dbg_value:
> +    case Intrinsic::dbg_label:
> +    case Intrinsic::lifetime_end:
> +      break;
> +    default:
> +      return false;
> +    }
> +  }
> +  return true;
> +}
> +
>  // Simplify resume that is only used by a single (non-phi) landing pad.
>  bool SimplifyCFGOpt::simplifySingleResume(ResumeInst *RI) {
>    BasicBlock *BB = RI->getParent();
> @@ -3970,10 +3992,8 @@ bool SimplifyCFGOpt::simplifySingleResume(ResumeInst *RI) {
>           "Resume must unwind the exception that caused control to here");
>
>    // Check that there are no other instructions except for debug intrinsics.
> -  BasicBlock::iterator I = LPInst->getIterator(), E = RI->getIterator();
> -  while (++I != E)
> -    if (!isa<DbgInfoIntrinsic>(I))
> -      return false;
> +  if (!isCleanupBlockEmpty(LPInst, RI))
> +    return false;
>
>    // Turn all invokes that unwind here into calls and delete the basic block.
>    for (pred_iterator PI = pred_begin(BB), PE = pred_end(BB); PI != PE;) {
> @@ -4009,23 +4029,8 @@ static bool removeEmptyCleanup(CleanupReturnInst *RI) {
>      return false;
>
>    // Check that there are no other instructions except for benign intrinsics.
> -  BasicBlock::iterator I = CPInst->getIterator(), E = RI->getIterator();
> -  while (++I != E) {
> -    auto *II = dyn_cast<IntrinsicInst>(I);
> -    if (!II)
> -      return false;
> -
> -    Intrinsic::ID IntrinsicID = II->getIntrinsicID();
> -    switch (IntrinsicID) {
> -    case Intrinsic::dbg_declare:
> -    case Intrinsic::dbg_value:
> -    case Intrinsic::dbg_label:
> -    case Intrinsic::lifetime_end:
> -      break;
> -    default:
> -      return false;
> -    }
> -  }
> +  if (!isCleanupBlockEmpty(CPInst, RI))
> +    return false;
>
>    // If the cleanup return we are simplifying unwinds to the caller, this will
>    // set UnwindDest to nullptr.
>
> diff  --git a/llvm/test/Transforms/SimplifyCFG/lifetime-landingpad.ll b/llvm/test/Transforms/SimplifyCFG/lifetime-landingpad.ll
> new file mode 100644
> index 000000000000..20424382b3be
> --- /dev/null
> +++ b/llvm/test/Transforms/SimplifyCFG/lifetime-landingpad.ll
> @@ -0,0 +1,33 @@
> +; RUN: opt < %s -simplifycfg -S | FileCheck %s
> +
> +; CHECK-LABEL: define void @foo
> +define void @foo() personality i32 (...)* @__gxx_personality_v0 {
> +entry:
> +; CHECK: alloca i8
> +; CHECK: call void @llvm.lifetime.start.p0i8
> +; CHECK: call void @bar()
> +; CHECK: call void @llvm.lifetime.end.p0i8
> +; CHECK: ret void
> +  %a = alloca i8
> +  call void @llvm.lifetime.start.p0i8(i64 1, i8* nonnull %a) nounwind
> +  invoke void @bar() to label %invoke.cont unwind label %lpad
> +
> +invoke.cont:
> +  call void @llvm.lifetime.end.p0i8(i64 1, i8* nonnull %a) nounwind
> +  ret void
> +
> +lpad:
> +; CHECK-NOT: landingpad
> +  %b = landingpad { i8*, i32 }
> +          cleanup
> +  call void @llvm.lifetime.end.p0i8(i64 1, i8* nonnull %a) nounwind
> +  resume { i8*, i32 } %b
> +}
> +
> +declare void @bar()
> +
> +declare void @llvm.lifetime.start.p0i8(i64 immarg, i8* nocapture) nounwind
> +
> +declare void @llvm.lifetime.end.p0i8(i64 immarg, i8* nocapture) nounwind
> +
> +declare i32 @__gxx_personality_v0(...)
>
>
>
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