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| author | Matthias Braun <matze@braunis.de> | 2016-07-09 00:19:07 +0000 |
|---|---|---|
| committer | Matthias Braun <matze@braunis.de> | 2016-07-09 00:19:07 +0000 |
| commit | 152e7c8b1222d2af61df72c08caaa740e553cb6c (patch) | |
| tree | 7178c1d1db0b5bf2babca7793c71c079854e1156 /llvm/test/CodeGen/X86/bitreverse.ll | |
| parent | 07985809abeb97c131d37ee389ee0fea2a646516 (diff) | |
| download | bcm5719-llvm-152e7c8b1222d2af61df72c08caaa740e553cb6c.tar.gz bcm5719-llvm-152e7c8b1222d2af61df72c08caaa740e553cb6c.zip | |
VirtRegMap: Replace some identity copies with KILL instructions.
An identity COPY like this:
%AL = COPY %AL, %EAX<imp-def>
has no semantic effect, but encodes liveness information: Further users
of %EAX only depend on this instruction even though it does not define
the full register.
Replace the COPY with a KILL instruction in those cases to maintain this
liveness information. (This reverts a small part of r238588 but this
time adds a comment explaining why a KILL instruction is useful).
llvm-svn: 274952
Diffstat (limited to 'llvm/test/CodeGen/X86/bitreverse.ll')
| -rw-r--r-- | llvm/test/CodeGen/X86/bitreverse.ll | 2 |
1 files changed, 2 insertions, 0 deletions
diff --git a/llvm/test/CodeGen/X86/bitreverse.ll b/llvm/test/CodeGen/X86/bitreverse.ll index 3b6280f16cd..f1b325a03eb 100644 --- a/llvm/test/CodeGen/X86/bitreverse.ll +++ b/llvm/test/CodeGen/X86/bitreverse.ll @@ -131,6 +131,8 @@ define <2 x i16> @test_bitreverse_v2i16(<2 x i16> %a) nounwind { ; CHECK-NEXT: shrl $15, %edx ; CHECK-NEXT: orl %esi, %edx ; CHECK-NEXT: orl %ecx, %edx +; CHECK-NEXT: # kill: %AX<def> %AX<kill> %EAX<kill> +; CHECK-NEXT: # kill: %DX<def> %DX<kill> %EDX<kill> ; CHECK-NEXT: popl %esi ; CHECK-NEXT: popl %edi ; CHECK-NEXT: retl |
