commit 8a23270ce60fdd5dafa1c8dfbf9f46c8efe244b7
author Nick Lewycky <nicholas@mxc.ca> Fri Jul 12 23:42:57 2013 +0000
committer Nick Lewycky <nicholas@mxc.ca> Fri Jul 12 23:42:57 2013 +0000
tree f0c7d5e97d2647ecb530397bf29b4add5350cc37
parent 434c0bd2a5c3c7ebaa8ca10dd7e4fdb1f25e92a0

Fix logic error optimizing "icmp pred (urem X, Y), Y" where pred is signed.
Fixes PR16605.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@186229 91177308-0d34-0410-b5e6-96231b3b80d8

lib/Analysis/InstructionSimplify.cpp

diff --git a/lib/Analysis/InstructionSimplify.cpp b/lib/Analysis/InstructionSimplify.cpp
index d66ecca..52c0456 100644
--- a/lib/Analysis/InstructionSimplify.cpp
+++ b/lib/Analysis/InstructionSimplify.cpp
@@ -2246,6 +2246,7 @@
     }
   }
 
+  // icmp pred (urem X, Y), Y
   if (LBO && match(LBO, m_URem(m_Value(), m_Specific(RHS)))) {
     bool KnownNonNegative, KnownNegative;
     switch (Pred) {
@@ -2253,7 +2254,7 @@
       break;
     case ICmpInst::ICMP_SGT:
     case ICmpInst::ICMP_SGE:
-      ComputeSignBit(LHS, KnownNonNegative, KnownNegative, Q.TD);
+      ComputeSignBit(RHS, KnownNonNegative, KnownNegative, Q.TD);
       if (!KnownNonNegative)
         break;
       // fall-through
@@ -2263,7 +2264,7 @@
       return getFalse(ITy);
     case ICmpInst::ICMP_SLT:
     case ICmpInst::ICMP_SLE:
-      ComputeSignBit(LHS, KnownNonNegative, KnownNegative, Q.TD);
+      ComputeSignBit(RHS, KnownNonNegative, KnownNegative, Q.TD);
       if (!KnownNonNegative)
         break;
       // fall-through
@@ -2273,6 +2274,8 @@
       return getTrue(ITy);
     }
   }
+
+  // icmp pred X, (urem Y, X)
   if (RBO && match(RBO, m_URem(m_Value(), m_Specific(LHS)))) {
     bool KnownNonNegative, KnownNegative;
     switch (Pred) {
@@ -2280,7 +2283,7 @@
       break;
     case ICmpInst::ICMP_SGT:
     case ICmpInst::ICMP_SGE:
-      ComputeSignBit(RHS, KnownNonNegative, KnownNegative, Q.TD);
+      ComputeSignBit(LHS, KnownNonNegative, KnownNegative, Q.TD);
       if (!KnownNonNegative)
         break;
       // fall-through
@@ -2290,7 +2293,7 @@
       return getTrue(ITy);
     case ICmpInst::ICMP_SLT:
     case ICmpInst::ICMP_SLE:
-      ComputeSignBit(RHS, KnownNonNegative, KnownNegative, Q.TD);
+      ComputeSignBit(LHS, KnownNonNegative, KnownNegative, Q.TD);
       if (!KnownNonNegative)
         break;
       // fall-through