[llvm-commits] [llvm] r73774 - in /llvm/trunk: lib/Analysis/IVUsers.cpp test/Transforms/LoopStrengthReduce/quadradic-exit-value.ll

[Dan Gohman]

Author: djg
Date: Fri Jun 19 12:33:15 2009
New Revision: 73774

URL: http://llvm.org/viewvc/llvm-project?rev=73774&view=rev
Log:
Don't (unconditionally) use getSCEVAtScope to simplify the step
expression in IVUsers, because in the case of a use of a non-linear
addrec outside of a loop, this causes the addrec to be evaluated as
a linear addrec.

Added:
    llvm/trunk/test/Transforms/LoopStrengthReduce/quadradic-exit-value.ll
Modified:
    llvm/trunk/lib/Analysis/IVUsers.cpp

Modified: llvm/trunk/lib/Analysis/IVUsers.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Analysis/IVUsers.cpp?rev=73774&r1=73773&r2=73774&view=diff

==============================================================================
--- llvm/trunk/lib/Analysis/IVUsers.cpp (original)
+++ llvm/trunk/lib/Analysis/IVUsers.cpp Fri Jun 19 12:33:15 2009
@@ -112,7 +112,6 @@
   SCEVHandle AddRecStart = AddRec->getStart();
   AddRecStart = SE->getSCEVAtScope(AddRecStart, UseLoop);
   SCEVHandle AddRecStride = AddRec->getStepRecurrence(*SE);
-  AddRecStride = SE->getSCEVAtScope(AddRecStride, UseLoop);
 
   // FIXME: If Start contains an SCEVAddRecExpr from a different loop, other
   // than an outer loop of the current loop, reject it.  LSR has no concept of

Added: llvm/trunk/test/Transforms/LoopStrengthReduce/quadradic-exit-value.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/LoopStrengthReduce/quadradic-exit-value.ll?rev=73774&view=auto

==============================================================================
--- llvm/trunk/test/Transforms/LoopStrengthReduce/quadradic-exit-value.ll (added)
+++ llvm/trunk/test/Transforms/LoopStrengthReduce/quadradic-exit-value.ll Fri Jun 19 12:33:15 2009
@@ -0,0 +1,18 @@
+; RUN: llvm-as < %s | opt -analyze -iv-users -disable-output | grep {Stride i64 {1,+,2}<loop>:}
+
+; The value of %r is dependent on a polynomial iteration expression.
+
+define i64 @foo(i64 %n) {
+entry:
+  br label %loop
+
+loop:
+  %indvar = phi i64 [ 0, %entry ], [ %indvar.next, %loop ]
+  %indvar.next = add i64 %indvar, 1
+  %c = icmp eq i64 %indvar.next, %n
+  br i1 %c, label %exit, label %loop
+
+exit:
+  %r = mul i64 %indvar, %indvar
+  ret i64 %r
+}