[llvm] r209694 - avoid type mismatch when building SCEVs

[Sebastian Pop]

Author: spop
Date: Tue May 27 17:42:00 2014
New Revision: 209694

URL: http://llvm.org/viewvc/llvm-project?rev=209694&view=rev
Log:
avoid type mismatch when building SCEVs

This is a corner case I have stumbled upon when dealing with ARM64 type
conversions. I was not able to extract a testcase for the community codebase to
fail on. The patch conservatively discards a division that would have ended up
in an ICE due to a type mismatch when building a multiply expression. I have
also added code to a place that builds add expressions and in which we should be
careful not to pass in operands of different types.

Modified:
    llvm/trunk/lib/Analysis/ScalarEvolution.cpp

Modified: llvm/trunk/lib/Analysis/ScalarEvolution.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Analysis/ScalarEvolution.cpp?rev=209694&r1=209693&r2=209694&view=diff
==============================================================================
--- llvm/trunk/lib/Analysis/ScalarEvolution.cpp (original)
+++ llvm/trunk/lib/Analysis/ScalarEvolution.cpp Tue May 27 17:42:00 2014
@@ -7131,9 +7131,19 @@ public:
 
   void visitAddExpr(const SCEVAddExpr *Numerator) {
     SmallVector<const SCEV *, 2> Qs, Rs;
+    Type *Ty = Denominator->getType();
+
     for (const SCEV *Op : Numerator->operands()) {
       const SCEV *Q, *R;
       divide(SE, Op, Denominator, &Q, &R);
+
+      // Bail out if types do not match.
+      if (Ty != Q->getType() || Ty != R->getType()) {
+        Quotient = Zero;
+        Remainder = Numerator;
+        return;
+      }
+
       Qs.push_back(Q);
       Rs.push_back(R);
     }
@@ -7150,9 +7160,17 @@ public:
 
   void visitMulExpr(const SCEVMulExpr *Numerator) {
     SmallVector<const SCEV *, 2> Qs;
+    Type *Ty = Denominator->getType();
 
     bool FoundDenominatorTerm = false;
     for (const SCEV *Op : Numerator->operands()) {
+      // Bail out if types do not match.
+      if (Ty != Op->getType()) {
+        Quotient = Zero;
+        Remainder = Numerator;
+        return;
+      }
+
       if (FoundDenominatorTerm) {
         Qs.push_back(Op);
         continue;
@@ -7165,6 +7183,14 @@ public:
         Qs.push_back(Op);
         continue;
       }
+
+      // Bail out if types do not match.
+      if (Ty != Q->getType()) {
+        Quotient = Zero;
+        Remainder = Numerator;
+        return;
+      }
+
       FoundDenominatorTerm = true;
       Qs.push_back(Q);
     }