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authorJakob Stoklund Olesen <stoklund@2pi.dk>2011-10-14 00:34:31 +0000
committerJakob Stoklund Olesen <stoklund@2pi.dk>2011-10-14 00:34:31 +0000
commita80444f88d88d88513b096c97474c453a4c3bcf6 (patch)
tree7ed57c205e7df23a1354b2f7a466ccadf78f1ded
parentdae36ba802f12966e4fc44d99097a55ff0b7d87b (diff)
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Add value numbers when spilling dead defs.
When spilling around an instruction with a dead def, remember to add a value number for the def. The missing value number wouldn't normally create problems since there would be an incoming live range as well. However, due to another bug we could spill a dead V_SET0 instruction which doesn't read any values. The missing value number caused an empty live range to be created which is dangerous since it doesn't interfere with anything. This fixes part of PR11125. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@141923 91177308-0d34-0410-b5e6-96231b3b80d8
-rw-r--r--lib/CodeGen/InlineSpiller.cpp10
-rw-r--r--test/CodeGen/X86/2011-10-11-SpillDead.ll19
2 files changed, 28 insertions, 1 deletions
diff --git a/lib/CodeGen/InlineSpiller.cpp b/lib/CodeGen/InlineSpiller.cpp
index b63611b94c..726af46965 100644
--- a/lib/CodeGen/InlineSpiller.cpp
+++ b/lib/CodeGen/InlineSpiller.cpp
@@ -1187,8 +1187,16 @@ void InlineSpiller::spillAroundUses(unsigned Reg) {
DEBUG(dbgs() << "\trewrite: " << Idx << '\t' << *MI);
// FIXME: Use a second vreg if instruction has no tied ops.
- if (Writes && hasLiveDef)
+ if (Writes) {
+ if (hasLiveDef)
insertSpill(NewLI, OldLI, Idx, MI);
+ else {
+ // This instruction defines a dead value. We don't need to spill it,
+ // but do create a live range for the dead value.
+ VNInfo *VNI = NewLI.getNextValue(Idx, 0, LIS.getVNInfoAllocator());
+ NewLI.addRange(LiveRange(Idx, Idx.getNextSlot(), VNI));
+ }
+ }
DEBUG(dbgs() << "\tinterval: " << NewLI << '\n');
}
diff --git a/test/CodeGen/X86/2011-10-11-SpillDead.ll b/test/CodeGen/X86/2011-10-11-SpillDead.ll
new file mode 100644
index 0000000000..8e70d6543a
--- /dev/null
+++ b/test/CodeGen/X86/2011-10-11-SpillDead.ll
@@ -0,0 +1,19 @@
+; RUN: llc < %s -verify-regalloc
+; PR11125
+target datalayout = "e-p:64:64:64-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:64:64-f32:32:32-f64:64:64-v64:64:64-v128:128:128-a0:0:64-s0:64:64-f80:128:128-n8:16:32:64-S128"
+target triple = "x86_64-apple-macosx10.7"
+
+; The inline asm takes %x as a GR32_ABCD virtual register.
+; The call to @g forces a spill of that register.
+;
+; The asm has a dead output tied to %x.
+; Verify that the spiller creates a value number for that dead def.
+;
+define void @f(i32 %x) nounwind uwtable ssp {
+entry:
+ tail call void @g() nounwind
+ %0 = tail call i32 asm sideeffect "foo $0", "=Q,0,~{ebx},~{dirflag},~{fpsr},~{flags}"(i32 %x) nounwind
+ ret void
+}
+
+declare void @g()