[llvm] r248743 - [SCEV] Don't crash on pointer comparisons

[Sanjoy Das via llvm-commits]

Author: sanjoy
Date: Mon Sep 28 16:14:32 2015
New Revision: 248743

URL: http://llvm.org/viewvc/llvm-project?rev=248743&view=rev
Log:
[SCEV] Don't crash on pointer comparisons

`ScalarEvolution::isImpliedCondOperandsViaNoOverflow` tries to cast the
operand type of the comparison it is given to an `IntegerType`.  This is
incorrect because it could actually be simplifying a comparison between
two pointers.  Switch it to using `getTypeSizeInBits` instead, which
does the right thing for both pointers and integers.

Fixed PR24956.

Added:
    llvm/trunk/test/Transforms/IndVarSimplify/pr24956.ll
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=248743&r1=248742&r2=248743&view=diff
==============================================================================
--- llvm/trunk/lib/Analysis/ScalarEvolution.cpp (original)
+++ llvm/trunk/lib/Analysis/ScalarEvolution.cpp Mon Sep 28 16:14:32 2015
@@ -7436,14 +7436,13 @@ bool ScalarEvolution::isImpliedCondOpera
   if (LDiff == 0)
     return true;
 
-  unsigned Width = cast<IntegerType>(RHS->getType())->getBitWidth();
   APInt FoundRHSLimit;
 
   if (Pred == CmpInst::ICMP_ULT) {
     FoundRHSLimit = -RDiff;
   } else {
     assert(Pred == CmpInst::ICMP_SLT && "Checked above!");
-    FoundRHSLimit = APInt::getSignedMinValue(Width) - RDiff;
+    FoundRHSLimit = APInt::getSignedMinValue(getTypeSizeInBits(RHS->getType())) - RDiff;
   }
 
   // Try to prove (1) or (2), as needed.

Added: llvm/trunk/test/Transforms/IndVarSimplify/pr24956.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/IndVarSimplify/pr24956.ll?rev=248743&view=auto
==============================================================================
--- llvm/trunk/test/Transforms/IndVarSimplify/pr24956.ll (added)
+++ llvm/trunk/test/Transforms/IndVarSimplify/pr24956.ll Mon Sep 28 16:14:32 2015
@@ -0,0 +1,37 @@
+; RUN: opt -S -indvars < %s | FileCheck %s
+
+; Check that this test does not crash.
+
+target datalayout = "e-m:o-i64:64-f80:128-n8:16:32:64-S128"
+target triple = "x86_64-apple-macosx10.10.0"
+
+define void @re_update_line(i8* %new) {
+; CHECK: @re_update_line(
+entry:
+  %incdec.ptr6 = getelementptr inbounds i8, i8* %new, i64 1
+  br label %for.cond.11.preheader
+
+for.cond.11.preheader:                            ; preds = %for.inc.26, %entry
+  %n.154 = phi i8* [ %new, %entry ], [ %incdec.ptr27, %for.inc.26 ]
+  %cmp12.52 = icmp ult i8* %n.154, %incdec.ptr6
+  br i1 %cmp12.52, label %land.rhs.16.lr.ph, label %for.inc.26
+
+land.rhs.16.lr.ph:                                ; preds = %for.cond.11.preheader
+  br label %land.rhs.16
+
+for.cond.11:                                      ; preds = %land.rhs.16
+  %incdec.ptr24 = getelementptr inbounds i8, i8* %p.053, i64 1
+  %cmp12 = icmp ult i8* %p.053, %new
+  br i1 %cmp12, label %land.rhs.16, label %for.inc.26
+
+land.rhs.16:                                      ; preds = %for.cond.11, %land.rhs.16.lr.ph
+  %p.053 = phi i8* [ %n.154, %land.rhs.16.lr.ph ], [ %incdec.ptr24, %for.cond.11 ]
+  br i1 undef, label %for.cond.11, label %for.inc.26
+
+for.inc.26:                                       ; preds = %land.rhs.16, %for.cond.11, %for.cond.11.preheader
+  %incdec.ptr27 = getelementptr inbounds i8, i8* %n.154, i64 1
+  br i1 false, label %for.cond.11.preheader, label %for.end.28
+
+for.end.28:                                       ; preds = %for.inc.26
+  ret void
+}