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author | Benjamin Kramer <benny.kra@googlemail.com> | 2010-07-08 11:39:10 +0000 |
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committer | Benjamin Kramer <benny.kra@googlemail.com> | 2010-07-08 11:39:10 +0000 |
commit | 1db071f0dae25d0c5a1af61ca71fa20d0a8e9370 (patch) | |
tree | 932a47f727c526ffbe4b42d99a819b9b3b669e83 /test/Transforms | |
parent | 67f8a7bc26c2993854a7e9ab43af362bc4477e3f (diff) | |
download | external_llvm-1db071f0dae25d0c5a1af61ca71fa20d0a8e9370.zip external_llvm-1db071f0dae25d0c5a1af61ca71fa20d0a8e9370.tar.gz external_llvm-1db071f0dae25d0c5a1af61ca71fa20d0a8e9370.tar.bz2 |
Teach instcombine to transform
(X >s -1) ? C1 : C2 and (X <s 0) ? C2 : C1
into ((X >>s 31) & (C2 - C1)) + C1, avoiding the conditional.
This optimization could be extended to take non-const C1 and C2 but we better
stay conservative to avoid code size bloat for now.
for
int sel(int n) {
return n >= 0 ? 60 : 100;
}
we now generate
sarl $31, %edi
andl $40, %edi
leal 60(%rdi), %eax
instead of
testl %edi, %edi
movl $60, %ecx
movl $100, %eax
cmovnsl %ecx, %eax
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@107866 91177308-0d34-0410-b5e6-96231b3b80d8
Diffstat (limited to 'test/Transforms')
-rw-r--r-- | test/Transforms/InstCombine/select.ll | 32 |
1 files changed, 32 insertions, 0 deletions
diff --git a/test/Transforms/InstCombine/select.ll b/test/Transforms/InstCombine/select.ll index 06d5338..246a7bc 100644 --- a/test/Transforms/InstCombine/select.ll +++ b/test/Transforms/InstCombine/select.ll @@ -438,3 +438,35 @@ define i32 @test34(i32 %x, i32 %y) { ; CHECK: @test34 ; CHECK: ret i32 %x } + +define i32 @test35(i32 %x) { + %cmp = icmp sge i32 %x, 0 + %cond = select i1 %cmp, i32 60, i32 100 + ret i32 %cond +; CHECK: @test35 +; CHECK: ashr i32 %x, 31 +; CHECK: and i32 {{.*}}, 40 +; CHECK: add i32 {{.*}}, 60 +; CHECK: ret +} + +define i32 @test36(i32 %x) { + %cmp = icmp slt i32 %x, 0 + %cond = select i1 %cmp, i32 60, i32 100 + ret i32 %cond +; CHECK: @test36 +; CHECK: ashr i32 %x, 31 +; CHECK: and i32 {{.*}}, -40 +; CHECK: add i32 {{.*}}, 100 +; CHECK: ret +} + +define i32 @test37(i32 %x) { + %cmp = icmp sgt i32 %x, -1 + %cond = select i1 %cmp, i32 1, i32 -1 + ret i32 %cond +; CHECK: @test37 +; CHECK: ashr i32 %x, 31 +; CHECK: or i32 {{.*}}, 1 +; CHECK: ret +} |