[llvm-commits] [llvm] r40866 - in /llvm/trunk: lib/Analysis/ScalarEvolution.cpp test/Analysis/ScalarEvolution/2007-09-06-MisinterpretBranch.ll

[Nick Lewycky]

Author: nicholas
Date: Mon Aug  6 13:33:46 2007
New Revision: 40866

URL: http://llvm.org/viewvc/llvm-project?rev=40866&view=rev
Log:
Don't assume it's safe to transform a loop just because it's dominated by any
comparison. Fixes bug 1598.

Added:
    llvm/trunk/test/Analysis/ScalarEvolution/2007-09-06-MisinterpretBranch.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=40866&r1=40865&r2=40866&view=diff

==============================================================================
--- llvm/trunk/lib/Analysis/ScalarEvolution.cpp (original)
+++ llvm/trunk/lib/Analysis/ScalarEvolution.cpp Mon Aug  6 13:33:46 2007
@@ -2387,7 +2387,7 @@
             return UnknownValue;  // Not a comparison against 'n-1'.
         }
         else return UnknownValue;
-      } else if (Cond == ICmpInst::ICMP_ULT)
+      } else
         return UnknownValue;
 
       // cerr << "Computed Loop Trip Count as: " 

Added: llvm/trunk/test/Analysis/ScalarEvolution/2007-09-06-MisinterpretBranch.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Analysis/ScalarEvolution/2007-09-06-MisinterpretBranch.ll?rev=40866&view=auto

==============================================================================
--- llvm/trunk/test/Analysis/ScalarEvolution/2007-09-06-MisinterpretBranch.ll (added)
+++ llvm/trunk/test/Analysis/ScalarEvolution/2007-09-06-MisinterpretBranch.ll Mon Aug  6 13:33:46 2007
@@ -0,0 +1,18 @@
+; RUN: llvm-as < %s | opt -indvars -adce -simplifycfg | llvm-dis | grep "icmp s"
+; PR1598
+
+define i32 @f(i32 %a, i32 %b, i32 %x, i32 %y) {
+entry:
+	%tmp3 = icmp eq i32 %a, %b		; <i1> [#uses=1]
+	br i1 %tmp3, label %return, label %bb
+
+bb:		; preds = %bb, %entry
+	%x_addr.0 = phi i32 [ %tmp6, %bb ], [ %x, %entry ]		; <i32> [#uses=1]
+	%tmp6 = add i32 %x_addr.0, 1		; <i32> [#uses=3]
+	%tmp9 = icmp slt i32 %tmp6, %y		; <i1> [#uses=1]
+	br i1 %tmp9, label %bb, label %return
+
+return:		; preds = %bb, %entry
+	%x_addr.1 = phi i32 [ %x, %entry ], [ %tmp6, %bb ]		; <i32> [#uses=1]
+	ret i32 %x_addr.1
+}