From: Davide Italiano <davide@freebsd.org>
Date: Tue, 10 May 2016 19:49:47 +0000 (+0000)
Subject: [SCCP] Partially propagate informations when the input is not fully defined.
X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=5f206cf7b0203c1c9d3d71838f3f4579864bf985;p=llvm

[SCCP] Partially propagate informations when the input is not fully defined.

With this patch:
%r1 = lshr i64 -1, 4294967296 -> undef

Before this patch:
%r1 = lshr i64 -1, 4294967296 -> 0

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@269105 91177308-0d34-0410-b5e6-96231b3b80d8
---

diff --git a/lib/Transforms/Scalar/SCCP.cpp b/lib/Transforms/Scalar/SCCP.cpp
index 75414ef3864..49748ff4c43 100644
--- a/lib/Transforms/Scalar/SCCP.cpp
+++ b/lib/Transforms/Scalar/SCCP.cpp
@@ -1331,6 +1331,9 @@ bool SCCPSolver::ResolvedUndefsIn(Function &F) {
         }
 
         Op1LV = getValueState(I.getOperand(1));
+
+        if (!Op0LV.isUndefined() && !Op1LV.isUndefined())
+          break;
       }
       // If this is an instructions whose result is defined even if the input is
       // not fully defined, propagate the information.
diff --git a/test/Transforms/ConstProp/shift.ll b/test/Transforms/ConstProp/shift.ll
index de23fe98ad8..91027096dd5 100644
--- a/test/Transforms/ConstProp/shift.ll
+++ b/test/Transforms/ConstProp/shift.ll
@@ -1,4 +1,5 @@
 ; RUN: opt < %s -constprop -S | FileCheck %s
+; RUN: opt < %s -sccp -S | FileCheck %s
 
 ; CHECK-LABEL: shift_undef_64
 define void @shift_undef_64(i64* %p) {