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| author | Roman Lebedev <lebedev.ri@gmail.com> | 2019-10-20 20:52:06 +0000 |
|---|---|---|
| committer | Roman Lebedev <lebedev.ri@gmail.com> | 2019-10-20 20:52:06 +0000 |
| commit | b93a52f5fec53c51628fa923f8a573f9f6ce2c98 (patch) | |
| tree | abb104ee4e7b8fd3f25181f164f62caf76912223 /test | |
| parent | 150b0bedb7f0aa3af89dbd75a3f046b76260c191 (diff) | |
[InstCombine] conditional sign-extend of high-bit-extract: 'or' pattern.
In this pattern, all the "magic" bits that we'd `add` are all
high sign bits, and in the value we'd be adding to they are all unset,
not unexpectedly, so we can have an `or` there:
https://rise4fun.com/Alive/ups
It is possible that `haveNoCommonBitsSet()` should be taught about this
pattern so that we never have an `add` variant, but the reasoning would
need to be recursive (because of that `select`), so i'm not really sure
that would be worth it just yet.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@375378 91177308-0d34-0410-b5e6-96231b3b80d8
Diffstat (limited to 'test')
| -rw-r--r-- | test/Transforms/InstCombine/conditional-variable-length-signext-after-high-bit-extract.ll | 6 |
1 files changed, 3 insertions, 3 deletions
diff --git a/test/Transforms/InstCombine/conditional-variable-length-signext-after-high-bit-extract.ll b/test/Transforms/InstCombine/conditional-variable-length-signext-after-high-bit-extract.ll index 3dc1fd244a3..cb4d38d6641 100644 --- a/test/Transforms/InstCombine/conditional-variable-length-signext-after-high-bit-extract.ll +++ b/test/Transforms/InstCombine/conditional-variable-length-signext-after-high-bit-extract.ll @@ -57,7 +57,7 @@ define i32 @t0_notrunc_or(i32 %data, i32 %nbits) { ; CHECK-NEXT: call void @use1(i1 [[SHOULD_SIGNEXT]]) ; CHECK-NEXT: call void @use32(i32 [[ALL_BITS_EXCEPT_LOW_NBITS]]) ; CHECK-NEXT: call void @use32(i32 [[MAGIC]]) -; CHECK-NEXT: [[SIGNEXTENDED:%.*]] = or i32 [[HIGH_BITS_EXTRACTED]], [[MAGIC]] +; CHECK-NEXT: [[SIGNEXTENDED:%.*]] = ashr i32 [[DATA]], [[LOW_BITS_TO_SKIP]] ; CHECK-NEXT: ret i32 [[SIGNEXTENDED]] ; %low_bits_to_skip = sub i32 32, %nbits @@ -152,14 +152,14 @@ define i32 @t2_trunc_or(i64 %data, i32 %nbits) { ; CHECK-NEXT: [[HIGH_BITS_EXTRACTED:%.*]] = trunc i64 [[HIGH_BITS_EXTRACTED_WIDE]] to i32 ; CHECK-NEXT: [[SHOULD_SIGNEXT:%.*]] = icmp slt i64 [[DATA]], 0 ; CHECK-NEXT: [[ALL_BITS_EXCEPT_LOW_NBITS:%.*]] = shl i32 -1, [[NBITS]] -; CHECK-NEXT: [[MAGIC:%.*]] = select i1 [[SHOULD_SIGNEXT]], i32 [[ALL_BITS_EXCEPT_LOW_NBITS]], i32 0 ; CHECK-NEXT: call void @use32(i32 [[LOW_BITS_TO_SKIP]]) ; CHECK-NEXT: call void @use64(i64 [[LOW_BITS_TO_SKIP_WIDE]]) ; CHECK-NEXT: call void @use64(i64 [[HIGH_BITS_EXTRACTED_WIDE]]) ; CHECK-NEXT: call void @use32(i32 [[HIGH_BITS_EXTRACTED]]) ; CHECK-NEXT: call void @use1(i1 [[SHOULD_SIGNEXT]]) ; CHECK-NEXT: call void @use32(i32 [[ALL_BITS_EXCEPT_LOW_NBITS]]) -; CHECK-NEXT: [[SIGNEXTENDED:%.*]] = or i32 [[MAGIC]], [[HIGH_BITS_EXTRACTED]] +; CHECK-NEXT: [[TMP1:%.*]] = ashr i64 [[DATA]], [[LOW_BITS_TO_SKIP_WIDE]] +; CHECK-NEXT: [[SIGNEXTENDED:%.*]] = trunc i64 [[TMP1]] to i32 ; CHECK-NEXT: ret i32 [[SIGNEXTENDED]] ; %low_bits_to_skip = sub i32 64, %nbits |