[PATCH] D20653: LICM: Do not sink or hoist assume intrinsic calls.

[Peter Collingbourne via llvm-commits]

pcc created this revision.
pcc added reviewers: dberlin, chandlerc, hfinkel, reames, sanjoy, boazo, majnemer.
pcc added a subscriber: llvm-commits.

This isn't useful, and it may result in assumes being removed.

This deals with more fallout from the AA change from rL268068.

http://reviews.llvm.org/D20653

Files:
  lib/Transforms/Scalar/LICM.cpp
  test/Transforms/LICM/assume.ll

Index: test/Transforms/LICM/assume.ll
===================================================================
--- /dev/null
+++ test/Transforms/LICM/assume.ll
@@ -0,0 +1,34 @@
+; RUN: opt -licm -basicaa < %s -S | FileCheck %s
+
+define void @f(i1 %p) nounwind ssp {
+entry:
+  br label %for.body
+
+for.body:
+  br i1 undef, label %if.then, label %for.cond.backedge
+
+for.cond.backedge:
+  br i1 undef, label %for.end104, label %for.body
+
+if.then:
+  br i1 undef, label %if.then27, label %if.end.if.end.split_crit_edge.critedge
+
+if.then27:
+; CHECK: tail call void @llvm.assume
+  tail call void @llvm.assume(i1 %p)
+  br label %for.body61.us
+
+if.end.if.end.split_crit_edge.critedge:
+  br label %for.body61
+
+for.body61.us:
+  br i1 undef, label %for.cond.backedge, label %for.body61.us
+
+for.body61:
+  br i1 undef, label %for.cond.backedge, label %for.body61
+
+for.end104:
+  ret void
+}
+
+declare void @llvm.assume(i1)
Index: lib/Transforms/Scalar/LICM.cpp
===================================================================
--- lib/Transforms/Scalar/LICM.cpp
+++ lib/Transforms/Scalar/LICM.cpp
@@ -438,9 +438,12 @@
 
     return !pointerInvalidatedByLoop(LI->getOperand(0), Size, AAInfo, CurAST);
   } else if (CallInst *CI = dyn_cast<CallInst>(&I)) {
-    // Don't sink or hoist dbg info; it's legal, but not useful.
-    if (isa<DbgInfoIntrinsic>(I))
-      return false;
+    // Don't sink or hoist dbg info or assumes; it's legal, but not useful.
+    if (auto *II = dyn_cast<IntrinsicInst>(&I)) {
+      if (isa<DbgInfoIntrinsic>(II) ||
+          II->getIntrinsicID() == Intrinsic::assume)
+        return false;
+    }
 
     // Don't sink calls which can throw.
     if (CI->mayThrow())


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