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llvm-project/llvm/test/CodeGen/X86/clz.ll

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Add i8 and i64 testing for ctlz on x86. Also simplify the i16 test. llvm-svn: 147249
2011-12-24 19:26:59 +08:00
; RUN: llc < %s -march=x86-64 -mcpu=yonah | FileCheck %s
Implement ctlz and cttz with bsr and bsf. llvm-svn: 45024
2007-12-14 10:13:44 +08:00
Add systematic testing for cttz as well, and fix the bug I spotted by inspection earlier. llvm-svn: 147250
2011-12-24 19:46:10 +08:00
declare i8 @llvm.cttz.i8(i8, i1)
declare i16 @llvm.cttz.i16(i16, i1)
Tidy up this rather crufty test. Put the declarations at the top to make my C-brain happy. Remove the unnecessary bits of pedantic IR fluff like nounwind. Remove stray uses comments. Name things semantically rather than tN so that adding a new test in the middle doesn't cause pain, and so that new tests can be grouped semantically. This exposes how little systematic testing is going on here. I noticed this by finding several bugs via inspection and wondering why this test wasn't catching any of them. =[ llvm-svn: 147248
2011-12-24 19:26:57 +08:00
declare i32 @llvm.cttz.i32(i32, i1)
Add systematic testing for cttz as well, and fix the bug I spotted by inspection earlier. llvm-svn: 147250
2011-12-24 19:46:10 +08:00
declare i64 @llvm.cttz.i64(i64, i1)
Add i8 and i64 testing for ctlz on x86. Also simplify the i16 test. llvm-svn: 147249
2011-12-24 19:26:59 +08:00
declare i8 @llvm.ctlz.i8(i8, i1)
Tidy up this rather crufty test. Put the declarations at the top to make my C-brain happy. Remove the unnecessary bits of pedantic IR fluff like nounwind. Remove stray uses comments. Name things semantically rather than tN so that adding a new test in the middle doesn't cause pain, and so that new tests can be grouped semantically. This exposes how little systematic testing is going on here. I noticed this by finding several bugs via inspection and wondering why this test wasn't catching any of them. =[ llvm-svn: 147248
2011-12-24 19:26:57 +08:00
declare i16 @llvm.ctlz.i16(i16, i1)
declare i32 @llvm.ctlz.i32(i32, i1)
Add i8 and i64 testing for ctlz on x86. Also simplify the i16 test. llvm-svn: 147249
2011-12-24 19:26:59 +08:00
declare i64 @llvm.ctlz.i64(i64, i1)
Implement ctlz and cttz with bsr and bsf. llvm-svn: 45024
2007-12-14 10:13:44 +08:00
Add systematic testing for cttz as well, and fix the bug I spotted by inspection earlier. llvm-svn: 147250
2011-12-24 19:46:10 +08:00
define i8 @cttz_i8(i8 %x) {
%tmp = call i8 @llvm.cttz.i8( i8 %x, i1 true )
ret i8 %tmp
; CHECK: cttz_i8:
; CHECK: bsfw
; CHECK-NOT: cmov
; CHECK: ret
}
define i16 @cttz_i16(i16 %x) {
%tmp = call i16 @llvm.cttz.i16( i16 %x, i1 true )
ret i16 %tmp
; CHECK: cttz_i16:
; CHECK: bsfw
; CHECK-NOT: cmov
; CHECK: ret
}
Tidy up this rather crufty test. Put the declarations at the top to make my C-brain happy. Remove the unnecessary bits of pedantic IR fluff like nounwind. Remove stray uses comments. Name things semantically rather than tN so that adding a new test in the middle doesn't cause pain, and so that new tests can be grouped semantically. This exposes how little systematic testing is going on here. I noticed this by finding several bugs via inspection and wondering why this test wasn't catching any of them. =[ llvm-svn: 147248
2011-12-24 19:26:57 +08:00
define i32 @cttz_i32(i32 %x) {
%tmp = call i32 @llvm.cttz.i32( i32 %x, i1 true )
Begin teaching the X86 target how to efficiently codegen patterns that use the zero-undefined variants of CTTZ and CTLZ. These are just simple patterns for now, there is more to be done to make real world code using these constructs be optimized and codegen'ed properly on X86. The existing tests are spiffed up to check that we no longer generate unnecessary cmov instructions, and that we generate the very important 'xor' to transform bsr which counts the index of the most significant one bit to the number of leading (most significant) zero bits. Also they now check that when the variant with defined zero result is used, the cmov is still produced. llvm-svn: 146974
2011-12-20 19:19:37 +08:00
ret i32 %tmp
Tidy up this rather crufty test. Put the declarations at the top to make my C-brain happy. Remove the unnecessary bits of pedantic IR fluff like nounwind. Remove stray uses comments. Name things semantically rather than tN so that adding a new test in the middle doesn't cause pain, and so that new tests can be grouped semantically. This exposes how little systematic testing is going on here. I noticed this by finding several bugs via inspection and wondering why this test wasn't catching any of them. =[ llvm-svn: 147248
2011-12-24 19:26:57 +08:00
; CHECK: cttz_i32:
filecheckize a test and mark these wiht a cpu so it passes on hosts without cmovs. llvm-svn: 98521
2010-03-15 06:31:16 +08:00
; CHECK: bsfl
Begin teaching the X86 target how to efficiently codegen patterns that use the zero-undefined variants of CTTZ and CTLZ. These are just simple patterns for now, there is more to be done to make real world code using these constructs be optimized and codegen'ed properly on X86. The existing tests are spiffed up to check that we no longer generate unnecessary cmov instructions, and that we generate the very important 'xor' to transform bsr which counts the index of the most significant one bit to the number of leading (most significant) zero bits. Also they now check that when the variant with defined zero result is used, the cmov is still produced. llvm-svn: 146974
2011-12-20 19:19:37 +08:00
; CHECK-NOT: cmov
; CHECK: ret
Implement ctlz and cttz with bsr and bsf. llvm-svn: 45024
2007-12-14 10:13:44 +08:00
}
Add systematic testing for cttz as well, and fix the bug I spotted by inspection earlier. llvm-svn: 147250
2011-12-24 19:46:10 +08:00
define i64 @cttz_i64(i64 %x) {
%tmp = call i64 @llvm.cttz.i64( i64 %x, i1 true )
ret i64 %tmp
; CHECK: cttz_i64:
; CHECK: bsfq
; CHECK-NOT: cmov
; CHECK: ret
}
Add i8 and i64 testing for ctlz on x86. Also simplify the i16 test. llvm-svn: 147249
2011-12-24 19:26:59 +08:00
define i8 @ctlz_i8(i8 %x) {
Fix ctlz and cttz. llvm definition requires them to return number of bits in of the src type when value is zero. llvm-svn: 45029
2007-12-14 16:30:15 +08:00
entry:
Add i8 and i64 testing for ctlz on x86. Also simplify the i16 test. llvm-svn: 147249
2011-12-24 19:26:59 +08:00
%tmp2 = call i8 @llvm.ctlz.i8( i8 %x, i1 true )
ret i8 %tmp2
; CHECK: ctlz_i8:
; CHECK: bsrl
; CHECK-NOT: cmov
; CHECK: xorl $7,
; CHECK: ret
}
define i16 @ctlz_i16(i16 %x) {
entry:
%tmp2 = call i16 @llvm.ctlz.i16( i16 %x, i1 true )
Begin teaching the X86 target how to efficiently codegen patterns that use the zero-undefined variants of CTTZ and CTLZ. These are just simple patterns for now, there is more to be done to make real world code using these constructs be optimized and codegen'ed properly on X86. The existing tests are spiffed up to check that we no longer generate unnecessary cmov instructions, and that we generate the very important 'xor' to transform bsr which counts the index of the most significant one bit to the number of leading (most significant) zero bits. Also they now check that when the variant with defined zero result is used, the cmov is still produced. llvm-svn: 146974
2011-12-20 19:19:37 +08:00
ret i16 %tmp2
Tidy up this rather crufty test. Put the declarations at the top to make my C-brain happy. Remove the unnecessary bits of pedantic IR fluff like nounwind. Remove stray uses comments. Name things semantically rather than tN so that adding a new test in the middle doesn't cause pain, and so that new tests can be grouped semantically. This exposes how little systematic testing is going on here. I noticed this by finding several bugs via inspection and wondering why this test wasn't catching any of them. =[ llvm-svn: 147248
2011-12-24 19:26:57 +08:00
; CHECK: ctlz_i16:
filecheckize a test and mark these wiht a cpu so it passes on hosts without cmovs. llvm-svn: 98521
2010-03-15 06:31:16 +08:00
; CHECK: bsrw
Begin teaching the X86 target how to efficiently codegen patterns that use the zero-undefined variants of CTTZ and CTLZ. These are just simple patterns for now, there is more to be done to make real world code using these constructs be optimized and codegen'ed properly on X86. The existing tests are spiffed up to check that we no longer generate unnecessary cmov instructions, and that we generate the very important 'xor' to transform bsr which counts the index of the most significant one bit to the number of leading (most significant) zero bits. Also they now check that when the variant with defined zero result is used, the cmov is still produced. llvm-svn: 146974
2011-12-20 19:19:37 +08:00
; CHECK-NOT: cmov
Switch the lowering of CTLZ_ZERO_UNDEF from a .td pattern back to the X86ISelLowering C++ code. Because this is lowered via an xor wrapped around a bsr, we want the dagcombine which runs after isel lowering to have a chance to clean things up. In particular, it is very common to see code which looks like: (sizeof(x)*8 - 1) ^ __builtin_clz(x) Which is trying to compute the most significant bit of 'x'. That's actually the value computed directly by the 'bsr' instruction, but if we match it too late, we'll get completely redundant xor instructions. The more naive code for the above (subtracting rather than using an xor) still isn't handled correctly due to the dagcombine getting confused. Also, while here fix an issue spotted by inspection: we should have been expanding the zero-undef variants to the normal variants when there is an 'lzcnt' instruction. Do so, and test for this. We don't want to generate unnecessary 'bsr' instructions. These two changes fix some regressions in encoding and decoding benchmarks. However, there is still a *lot* to be improve on in this type of code. llvm-svn: 147244
2011-12-24 18:55:54 +08:00
; CHECK: xorl $15,
Begin teaching the X86 target how to efficiently codegen patterns that use the zero-undefined variants of CTTZ and CTLZ. These are just simple patterns for now, there is more to be done to make real world code using these constructs be optimized and codegen'ed properly on X86. The existing tests are spiffed up to check that we no longer generate unnecessary cmov instructions, and that we generate the very important 'xor' to transform bsr which counts the index of the most significant one bit to the number of leading (most significant) zero bits. Also they now check that when the variant with defined zero result is used, the cmov is still produced. llvm-svn: 146974
2011-12-20 19:19:37 +08:00
; CHECK: ret
Fix ctlz and cttz. llvm definition requires them to return number of bits in of the src type when value is zero. llvm-svn: 45029
2007-12-14 16:30:15 +08:00
}
Tidy up this rather crufty test. Put the declarations at the top to make my C-brain happy. Remove the unnecessary bits of pedantic IR fluff like nounwind. Remove stray uses comments. Name things semantically rather than tN so that adding a new test in the middle doesn't cause pain, and so that new tests can be grouped semantically. This exposes how little systematic testing is going on here. I noticed this by finding several bugs via inspection and wondering why this test wasn't catching any of them. =[ llvm-svn: 147248
2011-12-24 19:26:57 +08:00
define i32 @ctlz_i32(i32 %x) {
%tmp = call i32 @llvm.ctlz.i32( i32 %x, i1 true )
ret i32 %tmp
; CHECK: ctlz_i32:
; CHECK: bsrl
; CHECK-NOT: cmov
; CHECK: xorl $31,
; CHECK: ret
}
- Teach SelectionDAG::isKnownNeverZero to return true (op x, c) when c is non-zero. - Teach X86 cmov optimization to eliminate the cmov from ctlz, cttz extension when the source of X86ISD::BSR / X86ISD::BSF is proven to be non-zero. rdar://9490949 llvm-svn: 131948
2011-05-24 09:48:22 +08:00
Add i8 and i64 testing for ctlz on x86. Also simplify the i16 test. llvm-svn: 147249
2011-12-24 19:26:59 +08:00
define i64 @ctlz_i64(i64 %x) {
%tmp = call i64 @llvm.ctlz.i64( i64 %x, i1 true )
ret i64 %tmp
; CHECK: ctlz_i64:
; CHECK: bsrq
; CHECK-NOT: cmov
; CHECK: xorq $63,
; CHECK: ret
}
Tidy up this rather crufty test. Put the declarations at the top to make my C-brain happy. Remove the unnecessary bits of pedantic IR fluff like nounwind. Remove stray uses comments. Name things semantically rather than tN so that adding a new test in the middle doesn't cause pain, and so that new tests can be grouped semantically. This exposes how little systematic testing is going on here. I noticed this by finding several bugs via inspection and wondering why this test wasn't catching any of them. =[ llvm-svn: 147248
2011-12-24 19:26:57 +08:00
define i32 @ctlz_i32_cmov(i32 %n) {
- Teach SelectionDAG::isKnownNeverZero to return true (op x, c) when c is non-zero. - Teach X86 cmov optimization to eliminate the cmov from ctlz, cttz extension when the source of X86ISD::BSR / X86ISD::BSF is proven to be non-zero. rdar://9490949 llvm-svn: 131948
2011-05-24 09:48:22 +08:00
entry:
Begin teaching the X86 target how to efficiently codegen patterns that use the zero-undefined variants of CTTZ and CTLZ. These are just simple patterns for now, there is more to be done to make real world code using these constructs be optimized and codegen'ed properly on X86. The existing tests are spiffed up to check that we no longer generate unnecessary cmov instructions, and that we generate the very important 'xor' to transform bsr which counts the index of the most significant one bit to the number of leading (most significant) zero bits. Also they now check that when the variant with defined zero result is used, the cmov is still produced. llvm-svn: 146974
2011-12-20 19:19:37 +08:00
; Generate a cmov to handle zero inputs when necessary.
Tidy up this rather crufty test. Put the declarations at the top to make my C-brain happy. Remove the unnecessary bits of pedantic IR fluff like nounwind. Remove stray uses comments. Name things semantically rather than tN so that adding a new test in the middle doesn't cause pain, and so that new tests can be grouped semantically. This exposes how little systematic testing is going on here. I noticed this by finding several bugs via inspection and wondering why this test wasn't catching any of them. =[ llvm-svn: 147248
2011-12-24 19:26:57 +08:00
; CHECK: ctlz_i32_cmov:
- Teach SelectionDAG::isKnownNeverZero to return true (op x, c) when c is non-zero. - Teach X86 cmov optimization to eliminate the cmov from ctlz, cttz extension when the source of X86ISD::BSR / X86ISD::BSF is proven to be non-zero. rdar://9490949 llvm-svn: 131948
2011-05-24 09:48:22 +08:00
; CHECK: bsrl
Begin teaching the X86 target how to efficiently codegen patterns that use the zero-undefined variants of CTTZ and CTLZ. These are just simple patterns for now, there is more to be done to make real world code using these constructs be optimized and codegen'ed properly on X86. The existing tests are spiffed up to check that we no longer generate unnecessary cmov instructions, and that we generate the very important 'xor' to transform bsr which counts the index of the most significant one bit to the number of leading (most significant) zero bits. Also they now check that when the variant with defined zero result is used, the cmov is still produced. llvm-svn: 146974
2011-12-20 19:19:37 +08:00
; CHECK: cmov
; CHECK: xorl $31,
; CHECK: ret
Tidy up this rather crufty test. Put the declarations at the top to make my C-brain happy. Remove the unnecessary bits of pedantic IR fluff like nounwind. Remove stray uses comments. Name things semantically rather than tN so that adding a new test in the middle doesn't cause pain, and so that new tests can be grouped semantically. This exposes how little systematic testing is going on here. I noticed this by finding several bugs via inspection and wondering why this test wasn't catching any of them. =[ llvm-svn: 147248
2011-12-24 19:26:57 +08:00
%tmp1 = call i32 @llvm.ctlz.i32(i32 %n, i1 false)
Begin teaching the X86 target how to efficiently codegen patterns that use the zero-undefined variants of CTTZ and CTLZ. These are just simple patterns for now, there is more to be done to make real world code using these constructs be optimized and codegen'ed properly on X86. The existing tests are spiffed up to check that we no longer generate unnecessary cmov instructions, and that we generate the very important 'xor' to transform bsr which counts the index of the most significant one bit to the number of leading (most significant) zero bits. Also they now check that when the variant with defined zero result is used, the cmov is still produced. llvm-svn: 146974
2011-12-20 19:19:37 +08:00
ret i32 %tmp1
}
Tidy up this rather crufty test. Put the declarations at the top to make my C-brain happy. Remove the unnecessary bits of pedantic IR fluff like nounwind. Remove stray uses comments. Name things semantically rather than tN so that adding a new test in the middle doesn't cause pain, and so that new tests can be grouped semantically. This exposes how little systematic testing is going on here. I noticed this by finding several bugs via inspection and wondering why this test wasn't catching any of them. =[ llvm-svn: 147248
2011-12-24 19:26:57 +08:00
define i32 @ctlz_i32_fold_cmov(i32 %n) {
Begin teaching the X86 target how to efficiently codegen patterns that use the zero-undefined variants of CTTZ and CTLZ. These are just simple patterns for now, there is more to be done to make real world code using these constructs be optimized and codegen'ed properly on X86. The existing tests are spiffed up to check that we no longer generate unnecessary cmov instructions, and that we generate the very important 'xor' to transform bsr which counts the index of the most significant one bit to the number of leading (most significant) zero bits. Also they now check that when the variant with defined zero result is used, the cmov is still produced. llvm-svn: 146974
2011-12-20 19:19:37 +08:00
entry:
; Don't generate the cmovne when the source is known non-zero (and bsr would
; not set ZF).
; rdar://9490949
Tidy up this rather crufty test. Put the declarations at the top to make my C-brain happy. Remove the unnecessary bits of pedantic IR fluff like nounwind. Remove stray uses comments. Name things semantically rather than tN so that adding a new test in the middle doesn't cause pain, and so that new tests can be grouped semantically. This exposes how little systematic testing is going on here. I noticed this by finding several bugs via inspection and wondering why this test wasn't catching any of them. =[ llvm-svn: 147248
2011-12-24 19:26:57 +08:00
; CHECK: ctlz_i32_fold_cmov:
Begin teaching the X86 target how to efficiently codegen patterns that use the zero-undefined variants of CTTZ and CTLZ. These are just simple patterns for now, there is more to be done to make real world code using these constructs be optimized and codegen'ed properly on X86. The existing tests are spiffed up to check that we no longer generate unnecessary cmov instructions, and that we generate the very important 'xor' to transform bsr which counts the index of the most significant one bit to the number of leading (most significant) zero bits. Also they now check that when the variant with defined zero result is used, the cmov is still produced. llvm-svn: 146974
2011-12-20 19:19:37 +08:00
; CHECK: bsrl
- Teach SelectionDAG::isKnownNeverZero to return true (op x, c) when c is non-zero. - Teach X86 cmov optimization to eliminate the cmov from ctlz, cttz extension when the source of X86ISD::BSR / X86ISD::BSF is proven to be non-zero. rdar://9490949 llvm-svn: 131948
2011-05-24 09:48:22 +08:00
; CHECK-NOT: cmov
Begin teaching the X86 target how to efficiently codegen patterns that use the zero-undefined variants of CTTZ and CTLZ. These are just simple patterns for now, there is more to be done to make real world code using these constructs be optimized and codegen'ed properly on X86. The existing tests are spiffed up to check that we no longer generate unnecessary cmov instructions, and that we generate the very important 'xor' to transform bsr which counts the index of the most significant one bit to the number of leading (most significant) zero bits. Also they now check that when the variant with defined zero result is used, the cmov is still produced. llvm-svn: 146974
2011-12-20 19:19:37 +08:00
; CHECK: xorl $31,
- Teach SelectionDAG::isKnownNeverZero to return true (op x, c) when c is non-zero. - Teach X86 cmov optimization to eliminate the cmov from ctlz, cttz extension when the source of X86ISD::BSR / X86ISD::BSF is proven to be non-zero. rdar://9490949 llvm-svn: 131948
2011-05-24 09:48:22 +08:00
; CHECK: ret
%or = or i32 %n, 1
Tidy up this rather crufty test. Put the declarations at the top to make my C-brain happy. Remove the unnecessary bits of pedantic IR fluff like nounwind. Remove stray uses comments. Name things semantically rather than tN so that adding a new test in the middle doesn't cause pain, and so that new tests can be grouped semantically. This exposes how little systematic testing is going on here. I noticed this by finding several bugs via inspection and wondering why this test wasn't catching any of them. =[ llvm-svn: 147248
2011-12-24 19:26:57 +08:00
%tmp1 = call i32 @llvm.ctlz.i32(i32 %or, i1 false)
- Teach SelectionDAG::isKnownNeverZero to return true (op x, c) when c is non-zero. - Teach X86 cmov optimization to eliminate the cmov from ctlz, cttz extension when the source of X86ISD::BSR / X86ISD::BSF is proven to be non-zero. rdar://9490949 llvm-svn: 131948
2011-05-24 09:48:22 +08:00
ret i32 %tmp1
}
Switch the lowering of CTLZ_ZERO_UNDEF from a .td pattern back to the X86ISelLowering C++ code. Because this is lowered via an xor wrapped around a bsr, we want the dagcombine which runs after isel lowering to have a chance to clean things up. In particular, it is very common to see code which looks like: (sizeof(x)*8 - 1) ^ __builtin_clz(x) Which is trying to compute the most significant bit of 'x'. That's actually the value computed directly by the 'bsr' instruction, but if we match it too late, we'll get completely redundant xor instructions. The more naive code for the above (subtracting rather than using an xor) still isn't handled correctly due to the dagcombine getting confused. Also, while here fix an issue spotted by inspection: we should have been expanding the zero-undef variants to the normal variants when there is an 'lzcnt' instruction. Do so, and test for this. We don't want to generate unnecessary 'bsr' instructions. These two changes fix some regressions in encoding and decoding benchmarks. However, there is still a *lot* to be improve on in this type of code. llvm-svn: 147244
2011-12-24 18:55:54 +08:00
Tidy up this rather crufty test. Put the declarations at the top to make my C-brain happy. Remove the unnecessary bits of pedantic IR fluff like nounwind. Remove stray uses comments. Name things semantically rather than tN so that adding a new test in the middle doesn't cause pain, and so that new tests can be grouped semantically. This exposes how little systematic testing is going on here. I noticed this by finding several bugs via inspection and wondering why this test wasn't catching any of them. =[ llvm-svn: 147248
2011-12-24 19:26:57 +08:00
define i32 @ctlz_bsr(i32 %n) {
Switch the lowering of CTLZ_ZERO_UNDEF from a .td pattern back to the X86ISelLowering C++ code. Because this is lowered via an xor wrapped around a bsr, we want the dagcombine which runs after isel lowering to have a chance to clean things up. In particular, it is very common to see code which looks like: (sizeof(x)*8 - 1) ^ __builtin_clz(x) Which is trying to compute the most significant bit of 'x'. That's actually the value computed directly by the 'bsr' instruction, but if we match it too late, we'll get completely redundant xor instructions. The more naive code for the above (subtracting rather than using an xor) still isn't handled correctly due to the dagcombine getting confused. Also, while here fix an issue spotted by inspection: we should have been expanding the zero-undef variants to the normal variants when there is an 'lzcnt' instruction. Do so, and test for this. We don't want to generate unnecessary 'bsr' instructions. These two changes fix some regressions in encoding and decoding benchmarks. However, there is still a *lot* to be improve on in this type of code. llvm-svn: 147244
2011-12-24 18:55:54 +08:00
entry:
; Don't generate any xors when a 'ctlz' intrinsic is actually used to compute
; the most significant bit, which is what 'bsr' does natively.
Tidy up this rather crufty test. Put the declarations at the top to make my C-brain happy. Remove the unnecessary bits of pedantic IR fluff like nounwind. Remove stray uses comments. Name things semantically rather than tN so that adding a new test in the middle doesn't cause pain, and so that new tests can be grouped semantically. This exposes how little systematic testing is going on here. I noticed this by finding several bugs via inspection and wondering why this test wasn't catching any of them. =[ llvm-svn: 147248
2011-12-24 19:26:57 +08:00
; CHECK: ctlz_bsr:
Switch the lowering of CTLZ_ZERO_UNDEF from a .td pattern back to the X86ISelLowering C++ code. Because this is lowered via an xor wrapped around a bsr, we want the dagcombine which runs after isel lowering to have a chance to clean things up. In particular, it is very common to see code which looks like: (sizeof(x)*8 - 1) ^ __builtin_clz(x) Which is trying to compute the most significant bit of 'x'. That's actually the value computed directly by the 'bsr' instruction, but if we match it too late, we'll get completely redundant xor instructions. The more naive code for the above (subtracting rather than using an xor) still isn't handled correctly due to the dagcombine getting confused. Also, while here fix an issue spotted by inspection: we should have been expanding the zero-undef variants to the normal variants when there is an 'lzcnt' instruction. Do so, and test for this. We don't want to generate unnecessary 'bsr' instructions. These two changes fix some regressions in encoding and decoding benchmarks. However, there is still a *lot* to be improve on in this type of code. llvm-svn: 147244
2011-12-24 18:55:54 +08:00
; CHECK: bsrl
; CHECK-NOT: xorl
; CHECK: ret
Tidy up this rather crufty test. Put the declarations at the top to make my C-brain happy. Remove the unnecessary bits of pedantic IR fluff like nounwind. Remove stray uses comments. Name things semantically rather than tN so that adding a new test in the middle doesn't cause pain, and so that new tests can be grouped semantically. This exposes how little systematic testing is going on here. I noticed this by finding several bugs via inspection and wondering why this test wasn't catching any of them. =[ llvm-svn: 147248
2011-12-24 19:26:57 +08:00
%ctlz = call i32 @llvm.ctlz.i32(i32 %n, i1 true)
Switch the lowering of CTLZ_ZERO_UNDEF from a .td pattern back to the X86ISelLowering C++ code. Because this is lowered via an xor wrapped around a bsr, we want the dagcombine which runs after isel lowering to have a chance to clean things up. In particular, it is very common to see code which looks like: (sizeof(x)*8 - 1) ^ __builtin_clz(x) Which is trying to compute the most significant bit of 'x'. That's actually the value computed directly by the 'bsr' instruction, but if we match it too late, we'll get completely redundant xor instructions. The more naive code for the above (subtracting rather than using an xor) still isn't handled correctly due to the dagcombine getting confused. Also, while here fix an issue spotted by inspection: we should have been expanding the zero-undef variants to the normal variants when there is an 'lzcnt' instruction. Do so, and test for this. We don't want to generate unnecessary 'bsr' instructions. These two changes fix some regressions in encoding and decoding benchmarks. However, there is still a *lot* to be improve on in this type of code. llvm-svn: 147244
2011-12-24 18:55:54 +08:00
%bsr = xor i32 %ctlz, 31
ret i32 %bsr
}
Tidy up this rather crufty test. Put the declarations at the top to make my C-brain happy. Remove the unnecessary bits of pedantic IR fluff like nounwind. Remove stray uses comments. Name things semantically rather than tN so that adding a new test in the middle doesn't cause pain, and so that new tests can be grouped semantically. This exposes how little systematic testing is going on here. I noticed this by finding several bugs via inspection and wondering why this test wasn't catching any of them. =[ llvm-svn: 147248
2011-12-24 19:26:57 +08:00
define i32 @ctlz_bsr_cmov(i32 %n) {
Switch the lowering of CTLZ_ZERO_UNDEF from a .td pattern back to the X86ISelLowering C++ code. Because this is lowered via an xor wrapped around a bsr, we want the dagcombine which runs after isel lowering to have a chance to clean things up. In particular, it is very common to see code which looks like: (sizeof(x)*8 - 1) ^ __builtin_clz(x) Which is trying to compute the most significant bit of 'x'. That's actually the value computed directly by the 'bsr' instruction, but if we match it too late, we'll get completely redundant xor instructions. The more naive code for the above (subtracting rather than using an xor) still isn't handled correctly due to the dagcombine getting confused. Also, while here fix an issue spotted by inspection: we should have been expanding the zero-undef variants to the normal variants when there is an 'lzcnt' instruction. Do so, and test for this. We don't want to generate unnecessary 'bsr' instructions. These two changes fix some regressions in encoding and decoding benchmarks. However, there is still a *lot* to be improve on in this type of code. llvm-svn: 147244
2011-12-24 18:55:54 +08:00
entry:
Tidy up this rather crufty test. Put the declarations at the top to make my C-brain happy. Remove the unnecessary bits of pedantic IR fluff like nounwind. Remove stray uses comments. Name things semantically rather than tN so that adding a new test in the middle doesn't cause pain, and so that new tests can be grouped semantically. This exposes how little systematic testing is going on here. I noticed this by finding several bugs via inspection and wondering why this test wasn't catching any of them. =[ llvm-svn: 147248
2011-12-24 19:26:57 +08:00
; Same as ctlz_bsr, but ensure this happens even when there is a potential
; zero.
; CHECK: ctlz_bsr_cmov:
Switch the lowering of CTLZ_ZERO_UNDEF from a .td pattern back to the X86ISelLowering C++ code. Because this is lowered via an xor wrapped around a bsr, we want the dagcombine which runs after isel lowering to have a chance to clean things up. In particular, it is very common to see code which looks like: (sizeof(x)*8 - 1) ^ __builtin_clz(x) Which is trying to compute the most significant bit of 'x'. That's actually the value computed directly by the 'bsr' instruction, but if we match it too late, we'll get completely redundant xor instructions. The more naive code for the above (subtracting rather than using an xor) still isn't handled correctly due to the dagcombine getting confused. Also, while here fix an issue spotted by inspection: we should have been expanding the zero-undef variants to the normal variants when there is an 'lzcnt' instruction. Do so, and test for this. We don't want to generate unnecessary 'bsr' instructions. These two changes fix some regressions in encoding and decoding benchmarks. However, there is still a *lot* to be improve on in this type of code. llvm-svn: 147244
2011-12-24 18:55:54 +08:00
; CHECK: bsrl
; CHECK-NOT: xorl
; CHECK: ret
Tidy up this rather crufty test. Put the declarations at the top to make my C-brain happy. Remove the unnecessary bits of pedantic IR fluff like nounwind. Remove stray uses comments. Name things semantically rather than tN so that adding a new test in the middle doesn't cause pain, and so that new tests can be grouped semantically. This exposes how little systematic testing is going on here. I noticed this by finding several bugs via inspection and wondering why this test wasn't catching any of them. =[ llvm-svn: 147248
2011-12-24 19:26:57 +08:00
%ctlz = call i32 @llvm.ctlz.i32(i32 %n, i1 false)
Switch the lowering of CTLZ_ZERO_UNDEF from a .td pattern back to the X86ISelLowering C++ code. Because this is lowered via an xor wrapped around a bsr, we want the dagcombine which runs after isel lowering to have a chance to clean things up. In particular, it is very common to see code which looks like: (sizeof(x)*8 - 1) ^ __builtin_clz(x) Which is trying to compute the most significant bit of 'x'. That's actually the value computed directly by the 'bsr' instruction, but if we match it too late, we'll get completely redundant xor instructions. The more naive code for the above (subtracting rather than using an xor) still isn't handled correctly due to the dagcombine getting confused. Also, while here fix an issue spotted by inspection: we should have been expanding the zero-undef variants to the normal variants when there is an 'lzcnt' instruction. Do so, and test for this. We don't want to generate unnecessary 'bsr' instructions. These two changes fix some regressions in encoding and decoding benchmarks. However, there is still a *lot* to be improve on in this type of code. llvm-svn: 147244
2011-12-24 18:55:54 +08:00
%bsr = xor i32 %ctlz, 31
ret i32 %bsr
}