[llvm] r249581 - Revert "Revert "This patch builds on top of D13378 to handle constant condition.""

[Adrian Prantl via llvm-commits]

> On Oct 7, 2015, at 11:14 AM, Mehdi Amini via llvm-commits <llvm-commits at lists.llvm.org> wrote:
> 
> Author: mehdi_amini
> Date: Wed Oct  7 13:14:25 2015
> New Revision: 249581
> 
> URL: http://llvm.org/viewvc/llvm-project?rev=249581&view=rev
> Log:
> Revert "Revert "This patch builds on top of D13378 to handle constant condition.""
> 
> This reverts commit r249528 and reapply r249431. The fix for the
> fallout has been commited in r249575.

Was this the same problem that caused

http://lab.llvm.org:8080/green/job/clang-stage2-configure-Rlto_build/6827/consoleFull#1038222285d489585b-5106-414a-ac11-3ff90657619c ?

-- adrian
> 
> From: Mehdi Amini <mehdi.amini at apple.com>
> 
> Added:
>    llvm/trunk/test/Analysis/ScalarEvolution/constant_condition.ll
> Modified:
>    llvm/trunk/lib/Analysis/ScalarEvolution.cpp
> 
> Modified: llvm/trunk/lib/Analysis/ScalarEvolution.cpp
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Analysis/ScalarEvolution.cpp?rev=249581&r1=249580&r2=249581&view=diff
> ==============================================================================
> --- llvm/trunk/lib/Analysis/ScalarEvolution.cpp (original)
> +++ llvm/trunk/lib/Analysis/ScalarEvolution.cpp Wed Oct  7 13:14:25 2015
> @@ -3904,6 +3904,11 @@ const SCEV *ScalarEvolution::createNodeF
>                                                       Value *Cond,
>                                                       Value *TrueVal,
>                                                       Value *FalseVal) {
> +  // Handle "constant" branch or select. This can occur for instance when a
> +  // loop pass transforms an inner loop and moves on to process the outer loop.
> +  if (auto *CI = dyn_cast<ConstantInt>(Cond))
> +    return getSCEV(CI->isOne() ? TrueVal : FalseVal);
> +
>   // Try to match some simple smax or umax patterns.
>   auto *ICI = dyn_cast<ICmpInst>(Cond);
>   if (!ICI)
> 
> Added: llvm/trunk/test/Analysis/ScalarEvolution/constant_condition.ll
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Analysis/ScalarEvolution/constant_condition.ll?rev=249581&view=auto
> ==============================================================================
> --- llvm/trunk/test/Analysis/ScalarEvolution/constant_condition.ll (added)
> +++ llvm/trunk/test/Analysis/ScalarEvolution/constant_condition.ll Wed Oct  7 13:14:25 2015
> @@ -0,0 +1,51 @@
> +; RUN: opt -analyze -scalar-evolution < %s | FileCheck %s
> +
> +define i32 @branch_true(i32 %x, i32 %y) {
> +; CHECK-LABEL: Classifying expressions for: @branch_true
> + entry:
> +  br i1 true, label %add, label %merge
> +
> + add:
> +  %sum = add i32 %x, %y
> +  br label %merge
> +
> + merge:
> +  %v = phi i32 [ %sum, %add ], [ %x, %entry ]
> +; CHECK:  %v = phi i32 [ %sum, %add ], [ %x, %entry ]
> +; CHECK-NEXT:  -->  (%x + %y) U: full-set S: full-set
> +  ret i32 %v
> +}
> +
> +define i32 @branch_false(i32 %x, i32 %y) {
> +; CHECK-LABEL: Classifying expressions for: @branch_false
> + entry:
> +  br i1 false, label %add, label %merge
> +
> + add:
> +  %sum = add i32 %x, %y
> +  br label %merge
> +
> + merge:
> +  %v = phi i32 [ %sum, %add ], [ %x, %entry ]
> +; CHECK:  %v = phi i32 [ %sum, %add ], [ %x, %entry ]
> +; CHECK-NEXT:  -->  %x U: full-set S: full-set
> +  ret i32 %v
> +}
> +
> +define i32 @select_true(i32 %x, i32 %y) {
> +; CHECK-LABEL: Classifying expressions for: @select_true
> + entry:
> + %v = select i1 true, i32 %x, i32 %y
> +; CHECK:  %v = select i1 true, i32 %x, i32 %y
> +; CHECK-NEXT:  -->  %x U: full-set S: full-set
> +  ret i32 %v
> +}
> +
> +define i32 @select_false(i32 %x, i32 %y) {
> +; CHECK-LABEL: Classifying expressions for: @select_false
> + entry:
> + %v = select i1 false, i32 %x, i32 %y
> +; CHECK:  %v = select i1 false, i32 %x, i32 %y
> +; CHECK-NEXT:  -->  %y U: full-set S: full-set
> +  ret i32 %v
> +}
> 
> 
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