[llvm] r221513 - SCCP: overdefined calls cannot become constant

[David Majnemer]

Author: majnemer
Date: Fri Nov  7 02:54:19 2014
New Revision: 221513

URL: http://llvm.org/viewvc/llvm-project?rev=221513&view=rev
Log:
SCCP: overdefined calls cannot become constant

We would attempt to fold away a call instruction which had been marked
overdefined.  However, it's not valid to transition to constant from
overdefined.

This fixes PR21512.

Modified:
    llvm/trunk/lib/Transforms/Scalar/SCCP.cpp
    llvm/trunk/test/Transforms/SCCP/ipsccp-basic.ll

Modified: llvm/trunk/lib/Transforms/Scalar/SCCP.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/Scalar/SCCP.cpp?rev=221513&r1=221512&r2=221513&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/Scalar/SCCP.cpp (original)
+++ llvm/trunk/lib/Transforms/Scalar/SCCP.cpp Fri Nov  7 02:54:19 2014
@@ -1107,6 +1107,9 @@ CallOverdefined:
         Operands.push_back(State.getConstant());
       }
 
+      if (getValueState(I).isOverdefined())
+        return;
+
       // If we can constant fold this, mark the result of the call as a
       // constant.
       if (Constant *C = ConstantFoldCall(F, Operands, TLI))

Modified: llvm/trunk/test/Transforms/SCCP/ipsccp-basic.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/SCCP/ipsccp-basic.ll?rev=221513&r1=221512&r2=221513&view=diff
==============================================================================
--- llvm/trunk/test/Transforms/SCCP/ipsccp-basic.ll (original)
+++ llvm/trunk/test/Transforms/SCCP/ipsccp-basic.ll Fri Nov  7 02:54:19 2014
@@ -227,3 +227,23 @@ entry:
 ; CHECK-LABEL: define internal i32 @test10b(
 ; CHECK: ret i32 undef
 }
+
+;;======================== test11
+
+define i64 @test11a() {
+  %xor = xor i64 undef, undef
+  ret i64 %xor
+; CHECK-LABEL: define i64 @test11a
+; CHECK: ret i64 0
+}
+
+define void @test11b() {
+  %call1 = call i64 @test11a()
+  %call2 = call i64 @llvm.ctpop.i64(i64 %call1)
+  ret void
+; CHECK-LABEL: define void @test11b
+; CHECK: %[[call1:.*]] = call i64 @test11a()
+; CHECK: %[[call2:.*]] = call i64 @llvm.ctpop.i64(i64 0)
+}
+
+declare i64 @llvm.ctpop.i64(i64)