[PATCH] D17127: [LoopRotate] Don't perform loop rotation if the loop header calls a convergent function.

[Justin Lebar via llvm-commits]

This revision was automatically updated to reflect the committed changes.
jlebar marked an inline comment as done.
Closed by commit rL260729: [LoopRotate] Don't perform loop rotation if the loop header calls a… (authored by jlebar).

Changed prior to commit:
  http://reviews.llvm.org/D17127?vs=47595&id=47841#toc

Repository:
  rL LLVM

http://reviews.llvm.org/D17127

Files:
  llvm/trunk/lib/Transforms/Scalar/LoopRotation.cpp
  llvm/trunk/test/Transforms/LoopRotate/convergent.ll

Index: llvm/trunk/test/Transforms/LoopRotate/convergent.ll
===================================================================
--- llvm/trunk/test/Transforms/LoopRotate/convergent.ll
+++ llvm/trunk/test/Transforms/LoopRotate/convergent.ll
@@ -0,0 +1,31 @@
+; RUN: opt -S -loop-rotate < %s | FileCheck %s
+
+ at e = global i32 10
+
+declare void @f1(i32) convergent
+declare void @f2(i32)
+
+; The call to f1 in the loop header shouldn't be duplicated (meaning, loop
+; rotation shouldn't occur), because f1 is convergent.
+
+; CHECK: call void @f1
+; CHECK-NOT: call void @f1
+
+define void @test(i32 %x) {
+entry:
+  br label %loop
+
+loop:
+  %n.phi = phi i32 [ %n, %loop.fin ], [ 0, %entry ]
+  call void @f1(i32 %n.phi)
+  %cond = icmp eq i32 %n.phi, %x
+  br i1 %cond, label %exit, label %loop.fin
+
+loop.fin:
+  %n = add i32 %n.phi, 1
+  call void @f2(i32 %n)
+  br label %loop
+
+exit:
+  ret void
+}
Index: llvm/trunk/lib/Transforms/Scalar/LoopRotation.cpp
===================================================================
--- llvm/trunk/lib/Transforms/Scalar/LoopRotation.cpp
+++ llvm/trunk/lib/Transforms/Scalar/LoopRotation.cpp
@@ -165,6 +165,11 @@
             << " instructions: "; L->dump());
       return false;
     }
+    if (Metrics.convergent) {
+      DEBUG(dbgs() << "LoopRotation: NOT rotating - contains convergent "
+                      "instructions: "; L->dump());
+      return false;
+    }
     if (Metrics.NumInsts > MaxHeaderSize)
       return false;
   }


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