Commit 18d41baa authored by Tanya Lattner's avatar Tanya Lattner
Browse files

Merge r98416 from mainline. 

Fix a typo in ValueTracking that's causing instcombine to delete needed shift instructions.

llvm-svn: 99289
parent 6fa23434

llvm/lib/Analysis/ValueTracking.cpp

+1 −1
Original line number Diff line number Diff line
@@ -779,7 +779,7 @@ unsigned llvm::ComputeNumSignBits(Value *V, const TargetData *TD, 
    for (unsigned i = 1, e = PN->getNumIncomingValues(); i != e; ++i) {

      if (Tmp == 1) return Tmp;

      Tmp = std::min(Tmp,

                     ComputeNumSignBits(PN->getIncomingValue(1), TD, Depth+1));

                     ComputeNumSignBits(PN->getIncomingValue(i), TD, Depth+1));

    }

    return Tmp;

  }

llvm/test/Transforms/InstCombine/shift-sra.ll

+20 −0
Original line number Diff line number Diff line
@@ -56,3 +56,23 @@ C: 
; CHECK: %P = phi i64

; CHECK-NEXT: ret i64 %P

}



; rdar://7732987

define i32 @test5(i32 %Y) {

  br i1 undef, label %A, label %C

A:

  br i1 undef, label %B, label %D

B:

  br label %D

C:

  br i1 undef, label %D, label %E

D:

  %P = phi i32 [0, %A], [0, %B], [%Y, %C] 

  %S = ashr i32 %P, 16

  ret i32 %S

; CHECK: @test5

; CHECK: %P = phi i32

; CHECK-NEXT: ashr i32 %P, 16

E:

  ret i32 0

}