Don't try to promote the same alloca twice. Fixes PR13916!

Chandler, it's not obvious that it's okay that this alloca gets into the list
twice to begin with. Please review and see whether this is the fix you really
want, but I wanted to get a fix checked in quickly.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@164634 91177308-0d34-0410-b5e6-96231b3b80d8

2 files changed, 28 insertions, 0 deletions

diff --git a/lib/Transforms/Scalar/SROA.cpp b/lib/Transforms/Scalar/SROA.cpp
index b3e63ae355..c33ee8fb87 100644
--- a/lib/Transforms/Scalar/SROA.cpp
+++ b/lib/Transforms/Scalar/SROA.cpp
@@ -3108,6 +3108,12 @@ bool SROA::promoteAllocas(Function &F) {
   if (PromotableAllocas.empty())
     return false;
 
+  // Ensure that the list is unique.
+  std::sort(PromotableAllocas.begin(), PromotableAllocas.end());
+  PromotableAllocas.erase(std::unique(PromotableAllocas.begin(),
+                                      PromotableAllocas.end()),
+                          PromotableAllocas.end());
+
   NumPromoted += PromotableAllocas.size();
 
   if (DT && !ForceSSAUpdater) {
diff --git a/test/Transforms/SROA/basictest.ll b/test/Transforms/SROA/basictest.ll
index a61de05f45..359a56a00d 100644
--- a/test/Transforms/SROA/basictest.ll
+++ b/test/Transforms/SROA/basictest.ll
@@ -855,3 +855,25 @@ entry:
   %result = or i8 %load, %load2
   ret i8 %result
 }
+
+%test22.struct = type { i8 }
+
+define void @test22() {
+; CHECK: @test22
+; CHECK-NOT: alloca
+; CHECK: ret void
+; PR13916
+entry:
+  %A = alloca %test22.struct
+  br i1 undef, label %if.then, label %if.end
+
+if.then:                                          ; preds = %entry
+  %tmp = bitcast %test22.struct* %A to i8*
+  %tmp1 = bitcast %test22.struct* %A to i8*
+  call void @llvm.memcpy.p0i8.p0i8.i32(i8* %tmp, i8* %tmp1, i32 1, i32 1, i1 false)
+  unreachable
+
+if.end:                                           ; preds = %entry
+  %tmp2 = load %test22.struct* %A
+  ret void
+}