[llvm] r291966 - [LoopStrengthReduce] Don't bother rewriting PHIs in catchswitch blocks

Hans Wennborg via llvm-commits llvm-commits at lists.llvm.org
Fri Jan 13 15:59:00 PST 2017


Should we merge this to the release branch?

On Fri, Jan 13, 2017 at 2:24 PM, David Majnemer via llvm-commits
<llvm-commits at lists.llvm.org> wrote:
> Author: majnemer
> Date: Fri Jan 13 16:24:27 2017
> New Revision: 291966
>
> URL: http://llvm.org/viewvc/llvm-project?rev=291966&view=rev
> Log:
> [LoopStrengthReduce] Don't bother rewriting PHIs in catchswitch blocks
>
> The catchswitch instruction cannot be split, don't bother trying to
> rewrite it.
>
> This fixes PR31627.
>
> Added:
>     llvm/trunk/test/Transforms/LoopStrengthReduce/pr31627.ll
> Modified:
>     llvm/trunk/lib/Transforms/Scalar/LoopStrengthReduce.cpp
>
> Modified: llvm/trunk/lib/Transforms/Scalar/LoopStrengthReduce.cpp
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/Scalar/LoopStrengthReduce.cpp?rev=291966&r1=291965&r2=291966&view=diff
> ==============================================================================
> --- llvm/trunk/lib/Transforms/Scalar/LoopStrengthReduce.cpp (original)
> +++ llvm/trunk/lib/Transforms/Scalar/LoopStrengthReduce.cpp Fri Jan 13 16:24:27 2017
> @@ -3163,6 +3163,9 @@ LSRInstance::CollectLoopInvariantFixupsA
>          // Don't bother if the instruction is in a BB which ends in an EHPad.
>          if (UseBB->getTerminator()->isEHPad())
>            continue;
> +        // Don't bother rewriting PHIs in catchswitch blocks.
> +        if (isa<CatchSwitchInst>(UserInst->getParent()->getTerminator()))
> +          continue;
>          // Ignore uses which are part of other SCEV expressions, to avoid
>          // analyzing them multiple times.
>          if (SE.isSCEVable(UserInst->getType())) {
> @@ -4672,7 +4675,8 @@ void LSRInstance::RewriteForPHI(PHINode
>        // is the canonical backedge for this loop, which complicates post-inc
>        // users.
>        if (e != 1 && BB->getTerminator()->getNumSuccessors() > 1 &&
> -          !isa<IndirectBrInst>(BB->getTerminator())) {
> +          !isa<IndirectBrInst>(BB->getTerminator()) &&
> +          !isa<CatchSwitchInst>(BB->getTerminator())) {
>          BasicBlock *Parent = PN->getParent();
>          Loop *PNLoop = LI.getLoopFor(Parent);
>          if (!PNLoop || Parent != PNLoop->getHeader()) {
>
> Added: llvm/trunk/test/Transforms/LoopStrengthReduce/pr31627.ll
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/LoopStrengthReduce/pr31627.ll?rev=291966&view=auto
> ==============================================================================
> --- llvm/trunk/test/Transforms/LoopStrengthReduce/pr31627.ll (added)
> +++ llvm/trunk/test/Transforms/LoopStrengthReduce/pr31627.ll Fri Jan 13 16:24:27 2017
> @@ -0,0 +1,58 @@
> +; RUN: opt -S -loop-reduce < %s | FileCheck %s
> +target datalayout = "e-m:w-i64:64-f80:128-n8:16:32:64-S128"
> +target triple = "x86_64-pc-windows-msvc19.0.24215"
> +
> +define void @fn3() personality i32 (...)* @__CxxFrameHandler3 {
> +entry:
> +  %call = invoke i32 @fn2()
> +          to label %for.cond.preheader unwind label %catch.dispatch2
> +
> +for.cond.preheader:                               ; preds = %entry
> +  br label %for.cond
> +
> +for.cond:                                         ; preds = %for.cond.preheader, %for.cond
> +  %b.0 = phi i32 [ %inc, %for.cond ], [ %call, %for.cond.preheader ]
> +  %inc = add nsw i32 %b.0, 1
> +  invoke void @fn1(i32 %inc)
> +          to label %for.cond unwind label %catch.dispatch
> +
> +; CHECK:   %[[add:.*]] = add i32 %call, 1
> +; CHECK:   br label %for.cond
> +
> +; CHECK: for.cond:                                         ; preds = %for.cond, %for.cond.preheader
> +; CHECK:   %[[lsr_iv:.*]] = phi i32 [ %lsr.iv.next, %for.cond ], [ %[[add]], %for.cond.preheader ]
> +; CHECK:   %[[lsr_iv_next:.*]] = add i32 %lsr.iv, 1
> +; CHECK:   invoke void @fn1(i32 %[[lsr_iv]])
> +
> +
> +catch.dispatch:                                   ; preds = %for.cond
> +  %0 = catchswitch within none [label %catch] unwind label %catch.dispatch2
> +
> +catch:                                            ; preds = %catch.dispatch
> +  %1 = catchpad within %0 [i8* null, i32 64, i8* null]
> +  invoke void @_CxxThrowException(i8* null, i8* null) #2 [ "funclet"(token %1) ]
> +          to label %unreachable unwind label %catch.dispatch2
> +
> +catch.dispatch2:                                  ; preds = %catch.dispatch, %catch, %entry
> +  %a.0 = phi i32 [ undef, %entry ], [ %call, %catch ], [ %call, %catch.dispatch ]
> +  %2 = catchswitch within none [label %catch3] unwind to caller
> +
> +catch3:                                           ; preds = %catch.dispatch2
> +  %3 = catchpad within %2 [i8* null, i32 64, i8* null]
> +  call void @fn1(i32 %a.0) [ "funclet"(token %3) ]
> +  catchret from %3 to label %try.cont4
> +
> +try.cont4:                                        ; preds = %catch3
> +  ret void
> +
> +unreachable:                                      ; preds = %catch
> +  unreachable
> +}
> +
> +declare i32 @fn2()
> +
> +declare i32 @__CxxFrameHandler3(...)
> +
> +declare void @fn1(i32)
> +
> +declare void @_CxxThrowException(i8*, i8*)
>
>
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