Avoid inserting noop's in the middle of a loop.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@60141 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/LoopAligner.cpp b/lib/CodeGen/LoopAligner.cpp
index b8d0059..b67f5c3 100644
--- a/lib/CodeGen/LoopAligner.cpp
+++ b/lib/CodeGen/LoopAligner.cpp
@@ -64,8 +64,14 @@
for (MachineFunction::iterator I = MF.begin(), E = MF.end(); I != E; ++I) {
MachineBasicBlock *MBB = I;
- if (MLI->isLoopHeader(MBB))
+ if (MLI->isLoopHeader(MBB)) {
+ MachineBasicBlock *PredBB = prior(I);
+ if (MLI->getLoopFor(MBB) == MLI->getLoopFor(PredBB))
+ // If previously BB is in the same loop, don't align this BB. We want
+ // to prevent adding noop's inside a loop.
+ continue;
MBB->setAlignment(Align);
+ }
}
return true;
diff --git a/test/CodeGen/X86/avoid-loop-align.ll b/test/CodeGen/X86/avoid-loop-align.ll
new file mode 100644
index 0000000..dfc5818
--- /dev/null
+++ b/test/CodeGen/X86/avoid-loop-align.ll
@@ -0,0 +1,32 @@
+; RUN: llvm-as < %s | llc -mtriple=i386-apple-darwin | grep align | count 1
+
+@A = common global [100 x i32] zeroinitializer, align 32 ; <[100 x i32]*> [#uses=1]
+
+define i8* @test(i8* %Q, i32* %L) nounwind {
+entry:
+ %tmp = tail call i32 (...)* @foo() nounwind ; <i32> [#uses=2]
+ %tmp1 = inttoptr i32 %tmp to i8* ; <i8*> [#uses=1]
+ br label %bb1
+
+bb: ; preds = %bb1, %bb1
+ %indvar.next = add i32 %P.0.rec, 1 ; <i32> [#uses=1]
+ br label %bb1
+
+bb1: ; preds = %bb, %entry
+ %P.0.rec = phi i32 [ 0, %entry ], [ %indvar.next, %bb ] ; <i32> [#uses=2]
+ %P.0 = getelementptr i8* %tmp1, i32 %P.0.rec ; <i8*> [#uses=3]
+ %tmp2 = load i8* %P.0, align 1 ; <i8> [#uses=1]
+ switch i8 %tmp2, label %bb4 [
+ i8 12, label %bb
+ i8 42, label %bb
+ ]
+
+bb4: ; preds = %bb1
+ %tmp3 = ptrtoint i8* %P.0 to i32 ; <i32> [#uses=1]
+ %tmp4 = sub i32 %tmp3, %tmp ; <i32> [#uses=1]
+ %tmp5 = getelementptr [100 x i32]* @A, i32 0, i32 %tmp4 ; <i32*> [#uses=1]
+ store i32 4, i32* %tmp5, align 4
+ ret i8* %P.0
+}
+
+declare i32 @foo(...)