From 5e6162e75645122b6afdbca8ba55294e073dc369 Mon Sep 17 00:00:00 2001
From: Eli Friedman <eli.friedman@gmail.com>
Date: Thu, 16 Feb 2012 00:41:10 +0000
Subject: [PATCH] =?utf8?q?loop-rotate=20shouldn't=20hoist=20alloca=20instr?=
 =?utf8?q?uctions=20out=20of=20a=20loop.=20=20Patch=20by=20Patrik=20H?=
 =?utf8?q?=C3=A4gglund,=20with=20slightly=20modified=20test.=20=20Issue=20?=
 =?utf8?q?reported=20by=20Patrik=20H=C3=A4gglund=20on=20llvmdev.?=
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git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@150642 91177308-0d34-0410-b5e6-96231b3b80d8
---
 lib/Transforms/Scalar/LoopRotation.cpp |  3 ++-
 test/Transforms/LoopRotate/alloca.ll   | 33 ++++++++++++++++++++++++++
 2 files changed, 35 insertions(+), 1 deletion(-)
 create mode 100644 test/Transforms/LoopRotate/alloca.ll

diff --git a/lib/Transforms/Scalar/LoopRotation.cpp b/lib/Transforms/Scalar/LoopRotation.cpp
index 7a60ad20474..59aace9e36d 100644
--- a/lib/Transforms/Scalar/LoopRotation.cpp
+++ b/lib/Transforms/Scalar/LoopRotation.cpp
@@ -339,7 +339,8 @@ bool LoopRotate::rotateLoop(Loop *L) {
     // memory (without proving that the loop doesn't write).
     if (L->hasLoopInvariantOperands(Inst) &&
         !Inst->mayReadFromMemory() && !Inst->mayWriteToMemory() &&
-        !isa<TerminatorInst>(Inst) && !isa<DbgInfoIntrinsic>(Inst)) {
+        !isa<TerminatorInst>(Inst) && !isa<DbgInfoIntrinsic>(Inst) &&
+        !isa<AllocaInst>(Inst)) {
       Inst->moveBefore(LoopEntryBranch);
       continue;
     }
diff --git a/test/Transforms/LoopRotate/alloca.ll b/test/Transforms/LoopRotate/alloca.ll
new file mode 100644
index 00000000000..fd217ea8dcf
--- /dev/null
+++ b/test/Transforms/LoopRotate/alloca.ll
@@ -0,0 +1,33 @@
+; RUN: opt < %s -loop-rotate -S | FileCheck %s
+
+; Test alloca in -loop-rotate.
+
+; We expect a different value for %ptr each iteration (according to the
+; definition of alloca). I.e. each @use must be paired with an alloca.
+
+; CHECK: call void @use(i8* %
+; CHECK: %ptr = alloca i8
+
+@e = global i16 10
+
+declare void @use(i8*)
+
+define void @test() {
+entry:
+  %end = load i16* @e
+  br label %loop
+
+loop:
+  %n.phi = phi i16 [ %n, %loop.fin ], [ 0, %entry ]
+  %ptr = alloca i8
+  %cond = icmp eq i16 %n.phi, %end
+  br i1 %cond, label %exit, label %loop.fin
+
+loop.fin:
+  %n = add i16 %n.phi, 1
+  call void @use(i8* %ptr)
+  br label %loop
+
+exit:
+  ret void
+}
-- 
2.34.1