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| author | Manman Ren <mren@apple.com> | 2012-05-10 16:48:21 +0000 |
|---|---|---|
| committer | Manman Ren <mren@apple.com> | 2012-05-10 16:48:21 +0000 |
| commit | 8ae4f062e4aefe60732b3fc135769aaedddf082d (patch) | |
| tree | 662271e4a9b9fce2b9fc6841b505ce6c3543e1a7 /test/CodeGen/ARM | |
| parent | 9df72a93ef27a27c6853eed3ed92c9e0b62c9ca6 (diff) | |
| download | external_llvm-8ae4f062e4aefe60732b3fc135769aaedddf082d.zip external_llvm-8ae4f062e4aefe60732b3fc135769aaedddf082d.tar.gz external_llvm-8ae4f062e4aefe60732b3fc135769aaedddf082d.tar.bz2 | |
ARM: peephole optimization to remove cmp instruction
This patch will optimize the following cases:
sub r1, r3 | sub r1, imm
cmp r3, r1 or cmp r1, r3 | cmp r1, imm
bge L1
TO
subs r1, r3
bge L1 or ble L1
If the branch instruction can use flag from "sub", then we can replace
"sub" with "subs" and eliminate the "cmp" instruction.
rdar: 10734411
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@156550 91177308-0d34-0410-b5e6-96231b3b80d8
Diffstat (limited to 'test/CodeGen/ARM')
| -rw-r--r-- | test/CodeGen/ARM/sub-cmp-peephole.ll | 34 |
1 files changed, 34 insertions, 0 deletions
diff --git a/test/CodeGen/ARM/sub-cmp-peephole.ll b/test/CodeGen/ARM/sub-cmp-peephole.ll new file mode 100644 index 0000000..b3a9dc5 --- /dev/null +++ b/test/CodeGen/ARM/sub-cmp-peephole.ll @@ -0,0 +1,34 @@ +; RUN: llc < %s -march=arm | FileCheck %s + +define i32 @f(i32 %a, i32 %b) nounwind ssp { +entry: +; CHECK: _f: +; CHECK: subs +; CHECK-NOT: cmp + %cmp = icmp sgt i32 %a, %b + %sub = sub nsw i32 %a, %b + %sub. = select i1 %cmp, i32 %sub, i32 0 + ret i32 %sub. +} + +define i32 @g(i32 %a, i32 %b) nounwind ssp { +entry: +; CHECK: _g: +; CHECK: subs +; CHECK-NOT: cmp + %cmp = icmp slt i32 %a, %b + %sub = sub nsw i32 %b, %a + %sub. = select i1 %cmp, i32 %sub, i32 0 + ret i32 %sub. +} + +define i32 @h(i32 %a, i32 %b) nounwind ssp { +entry: +; CHECK: _h: +; CHECK: subs +; CHECK-NOT: cmp + %cmp = icmp sgt i32 %a, 3 + %sub = sub nsw i32 %a, 3 + %sub. = select i1 %cmp, i32 %sub, i32 %b + ret i32 %sub. +} |