Fix PR2358 by resolving calls with undef arguments to overdefined.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@51535 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/lib/Transforms/Scalar/SCCP.cpp b/lib/Transforms/Scalar/SCCP.cpp
index 79cda33f79319888d7e1874a2acf9cb4b24515a5..da715acd29b5f77ff08fae341a9b1263a2886ae6 100644 (file)
--- a/lib/Transforms/Scalar/SCCP.cpp
+++ b/lib/Transforms/Scalar/SCCP.cpp
@@ -1370,6 +1370,12 @@ bool SCCPSolver::ResolvedUndefsIn(Function &F) {
         else
           markOverdefined(LV, I);
         return true;
+      case Instruction::Call:
+        // If a call has an undef result, it is because it is constant foldable
+        // but one of the inputs was undef.  Just force the result to
+        // overdefined.
+        markOverdefined(LV, I);
+        return true;
       }
     }
   

diff --git a/test/Transforms/SCCP/2008-05-23-UndefCallFold.ll b/test/Transforms/SCCP/2008-05-23-UndefCallFold.ll
new file mode 100644 (file)
index 0000000..f85a362
--- /dev/null
+++ b/test/Transforms/SCCP/2008-05-23-UndefCallFold.ll
@@ -0,0 +1,14 @@
+; RUN: llvm-as < %s | opt -sccp | llvm-dis | not grep {ret i32 undef}
+; PR2358
+target datalayout =
+"e-p:32:32:32-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:32:64-f32:32:32-f64:32:64-v64:64:64-v128:128:128-a0:0:64-f80:128:128"
+target triple = "i686-pc-linux-gnu"
+
+define i32 @x(i32 %b) {
+entry:
+ %val = call i32 @llvm.cttz.i32(i32 undef)
+ ret i32 %val
+}
+
+declare i32 @llvm.cttz.i32(i32)
+