Make sure the whole live range is covered when values are pruned twice.

JoinVals::pruneValues() calls LIS->pruneValue() to avoid conflicts when
overlapping two different values. This produces a set of live range end
points that are used to reconstruct the live range (with SSA update)
after joining the two registers.

When a value is pruned twice, the set of end points was insufficient:

  v1 = DEF
  v1 = REPLACE1
  v1 = REPLACE2
  KILL v1

The end point at KILL would only reconstruct the live range from
REPLACE2 to KILL, leaving the range REPLACE1-REPLACE2 dead.

Add REPLACE2 as an end point in this case so the full live range is
reconstructed.

This fixes PR13999.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@165056 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 26 insertions, 1 deletions

diff --git a/test/CodeGen/ARM/coalesce-subregs.ll b/test/CodeGen/ARM/coalesce-subregs.ll
index 8d7ded5be0..6e1f17dced 100644
--- a/test/CodeGen/ARM/coalesce-subregs.ll
+++ b/test/CodeGen/ARM/coalesce-subregs.ll
@@ -1,4 +1,4 @@
-; RUN: llc < %s -mcpu=cortex-a9 -new-coalescer | FileCheck %s
+; RUN: llc < %s -mcpu=cortex-a9 -verify-coalescing | FileCheck %s
 target datalayout = "e-p:32:32:32-i1:8:32-i8:8:32-i16:16:32-i32:32:32-i64:32:64-f32:32:32-f64:32:64-v64:32:64-v128:32:128-a0:0:32-n32-S32"
 target triple = "thumbv7-apple-ios0.0.0"
 
@@ -189,3 +189,28 @@ if.end:                                           ; preds = %entry, %if.then
 declare <4 x float> @llvm.arm.neon.vld1.v4f32(i8*, i32) nounwind readonly
 
 declare void @llvm.arm.neon.vst1.v4f32(i8*, <4 x float>, i32) nounwind
+
+; CHECK: pr13999
+define void @pr13999() nounwind readonly {
+entry:
+ br i1 true, label %outer_loop, label %loop.end
+
+outer_loop:
+ %d = phi double [ 0.0, %entry ], [ %add, %after_inner_loop ]
+ %0 = insertelement <2 x double> <double 0.0, double 0.0>, double %d, i32 0
+ br i1 undef, label %after_inner_loop, label %inner_loop
+
+inner_loop:
+ br i1 true, label %after_inner_loop, label %inner_loop
+
+after_inner_loop:
+ %1 = phi <2 x double> [ %0, %outer_loop ], [ <double 0.0, double 0.0>,
+%inner_loop ]
+ %2 = extractelement <2 x double> %1, i32 1
+ %add = fadd double 1.0, %2
+ br i1 false, label %loop.end, label %outer_loop
+
+loop.end:
+ %d.end = phi double [ 0.0, %entry ], [ %add, %after_inner_loop ]
+ ret void
+}