From 6165dba25f3374ce340b420ab9a360623c26fdc3 Mon Sep 17 00:00:00 2001
From: Nadav Rotem <nrotem@apple.com>
Date: Mon, 10 Sep 2012 18:51:09 +0000
Subject: [PATCH] Stack Coloring: Handle the case where END markers come before
 BEGIN markers properly.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@163530 91177308-0d34-0410-b5e6-96231b3b80d8
---
 lib/CodeGen/StackColoring.cpp     | 12 ++++++++++++
 test/CodeGen/X86/StackColoring.ll | 27 +++++++++++++++++++++++++++
 2 files changed, 39 insertions(+)

diff --git a/lib/CodeGen/StackColoring.cpp b/lib/CodeGen/StackColoring.cpp
index 462a134ace3..927ecef1716 100644
--- a/lib/CodeGen/StackColoring.cpp
+++ b/lib/CodeGen/StackColoring.cpp
@@ -315,6 +315,18 @@ void StackColoring::calculateLocalLiveness() {
       LocalLiveOut.reset(BlockLiveness[BB].End);
       LocalLiveIn.reset(BlockLiveness[BB].Begin);
 
+      // If we have both BEGIN and END markers in the same basic block then
+      // we know that the BEGIN marker comes after the END, because we already
+      // handle the case where the BEGIN comes before the END when collecting
+      // the markers (and building the BEGIN/END vectore).
+      // Want to enable the LIVE_IN and LIVE_OUT of slots that have both
+      // BEGIN and END because it means that the value lives before and after
+      // this basic block.
+      BitVector LocalEndBegin = BlockLiveness[BB].End;
+      LocalEndBegin &= BlockLiveness[BB].Begin;
+      LocalLiveIn |= LocalEndBegin;
+      LocalLiveOut |= LocalEndBegin;
+
       if (LocalLiveIn.test(BlockLiveness[BB].LiveIn)) {
         changed = true;
         BlockLiveness[BB].LiveIn |= LocalLiveIn;
diff --git a/test/CodeGen/X86/StackColoring.ll b/test/CodeGen/X86/StackColoring.ll
index 6ef3b3cd023..0f36ce29b9a 100644
--- a/test/CodeGen/X86/StackColoring.ll
+++ b/test/CodeGen/X86/StackColoring.ll
@@ -325,6 +325,33 @@ entry:
   ret void
 }
 
+
+;YESCOLOR: subq  $272, %rsp
+;NOCOLOR: subq  $272, %rsp
+
+define i32 @myCall_end_before_begin(i32 %in, i1 %d) {
+entry:
+  %a = alloca [17 x i8*], align 8
+  %a2 = alloca [16 x i8*], align 8
+  %b = bitcast [17 x i8*]* %a to i8*
+  %b2 = bitcast [16 x i8*]* %a2 to i8*
+  %t1 = call i32 @foo(i32 %in, i8* %b)
+  %t2 = call i32 @foo(i32 %in, i8* %b)
+  call void @llvm.lifetime.end(i64 -1, i8* %b)
+  call void @llvm.lifetime.start(i64 -1, i8* %b)
+  br i1 %d, label %bb2, label %bb3
+bb2:
+  call void @llvm.lifetime.start(i64 -1, i8* %b2)
+  %t3 = call i32 @foo(i32 %in, i8* %b2)
+  %t4 = call i32 @foo(i32 %in, i8* %b2)
+  %t5 = add i32 %t1, %t2
+  %t6 = add i32 %t3, %t4
+  %t7 = add i32 %t5, %t6
+  ret i32 %t7
+bb3:
+  ret i32 0
+}
+
 declare void @bar([100 x i32]* , [100 x i32]*) nounwind
 
 declare void @llvm.lifetime.start(i64, i8* nocapture) nounwind
-- 
2.34.1