diff options
| 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/anyext.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/anyext.ll')
| -rw-r--r-- | llvm/test/CodeGen/X86/anyext.ll | 4 |
1 files changed, 4 insertions, 0 deletions
diff --git a/llvm/test/CodeGen/X86/anyext.ll b/llvm/test/CodeGen/X86/anyext.ll index 3c53983fe4e..4f4218bdd63 100644 --- a/llvm/test/CodeGen/X86/anyext.ll +++ b/llvm/test/CodeGen/X86/anyext.ll @@ -8,6 +8,7 @@ define i32 @foo(i32 %p, i8 zeroext %x) nounwind { ; X32-LABEL: foo: ; X32: # BB#0: ; X32-NEXT: movzbl {{[0-9]+}}(%esp), %eax +; X32-NEXT: # kill: %EAX<def> %EAX<kill> %AX<def> ; X32-NEXT: divb {{[0-9]+}}(%esp) ; X32-NEXT: movzbl %al, %eax ; X32-NEXT: andl $1, %eax @@ -16,6 +17,7 @@ define i32 @foo(i32 %p, i8 zeroext %x) nounwind { ; X64-LABEL: foo: ; X64: # BB#0: ; X64-NEXT: movzbl %dil, %eax +; X64-NEXT: # kill: %EAX<def> %EAX<kill> %AX<def> ; X64-NEXT: divb %sil ; X64-NEXT: movzbl %al, %eax ; X64-NEXT: andl $1, %eax @@ -33,6 +35,7 @@ define i32 @bar(i32 %p, i16 zeroext %x) nounwind { ; X32-NEXT: movzwl {{[0-9]+}}(%esp), %eax ; X32-NEXT: xorl %edx, %edx ; X32-NEXT: divw {{[0-9]+}}(%esp) +; X32-NEXT: # kill: %AX<def> %AX<kill> %EAX<def> ; X32-NEXT: andl $1, %eax ; X32-NEXT: retl ; @@ -41,6 +44,7 @@ define i32 @bar(i32 %p, i16 zeroext %x) nounwind { ; X64-NEXT: xorl %edx, %edx ; X64-NEXT: movl %edi, %eax ; X64-NEXT: divw %si +; X64-NEXT: # kill: %AX<def> %AX<kill> %EAX<def> ; X64-NEXT: andl $1, %eax ; X64-NEXT: retq %q = trunc i32 %p to i16 |
