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[X86][GlobalIsel] support G_FABS #136718

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Merged
merged 16 commits into from
Jun 25, 2025
Merged

[X86][GlobalIsel] support G_FABS #136718

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d4475cb
[X86][GlobalIsel] support fabs for f80
Apr 22, 2025
22e2c83
add float and double
Apr 24, 2025
0ed32a7
update test
May 1, 2025
8221bc6
remove s8
May 1, 2025
6a58699
update fabs for f32 and f64
May 27, 2025
db0e1cb
fix indent
May 27, 2025
f35b674
add x87 specific runs
Jun 3, 2025
2782568
fix tst
Jun 5, 2025
860903d
remove unused marker
Jun 5, 2025
d4d3d44
fix clang format
Jun 7, 2025
4838b22
fix clang format
Jun 7, 2025
63eebe0
remove const pool
Jun 11, 2025
a718a5b
remove noise
Jun 11, 2025
e57ab03
add fallback
Jun 19, 2025
f5e5274
format extension issue
Jun 19, 2025
ac44b20
Merge branch 'main' into gisel_fabs
RKSimon Jun 25, 2025
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4 changes: 4 additions & 0 deletions llvm/lib/Target/X86/GISel/X86LegalizerInfo.cpp
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Expand Up @@ -466,6 +466,10 @@ X86LegalizerInfo::X86LegalizerInfo(const X86Subtarget &STI,
(UseX87 && typeInSet(0, {s80})(Query));
});

getActionDefinitionsBuilder(G_FABS)
.legalFor(UseX87 && !HasSSE2 && !HasSSE1, {s32, s64, s80})
.lower();
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@e-kud e-kud Apr 22, 2025

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Does lower generate the selectable code? Then we probably can add tests for float and double as well.

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@mahesh-attarde mahesh-attarde Apr 23, 2025

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+x87,-sse,-sse2 restricts SDAG Isel for float and double. It requires SSE.
exact message SSE register return with SSE disabled.

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@arsenm arsenm Apr 23, 2025

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that error comes from the globalisel code, not sdag. You can also just stop testing with those features forced off

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@e-kud e-kud Apr 23, 2025

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We use X87 with and without SSE for s80. So there is no need forcing -sse.

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@mahesh-attarde mahesh-attarde Apr 23, 2025

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that error comes from the globalisel code, not sdag. You can also just stop testing with those features forced off
@arsenm It appeared without gisel too.
https://godbolt.org/z/Goc3zs9qe
@e-kud I can drop using -sse 👍


// fp comparison
getActionDefinitionsBuilder(G_FCMP)
.legalFor(HasSSE1 || UseX87, {s8, s32})
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2 changes: 2 additions & 0 deletions llvm/test/CodeGen/X86/isel-fabs-x87.ll
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@@ -1,8 +1,10 @@
; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py UTC_ARGS: --version 5
; RUN: llc < %s -mtriple=x86_64-- -mattr=+x87,-sse2,-sse | FileCheck %s --check-prefixes=X64
; RUN: llc < %s -mtriple=x86_64-- -mattr=+x87,-sse2,-sse -fast-isel -fast-isel-abort=1 | FileCheck %s --check-prefixes=X64
; RUN: llc < %s -mtriple=x86_64-- -mattr=+x87,-sse2,-sse -global-isel -global-isel-abort=1 | FileCheck %s --check-prefixes=X64
; RUN: llc < %s -mtriple=i686-- -mattr=+x87,-sse2,-sse | FileCheck %s --check-prefixes=X86
; RUN: llc < %s -mtriple=i686-- -mattr=+x87,-sse2,-sse -fast-isel -fast-isel-abort=1 | FileCheck %s --check-prefixes=X86
; RUN: llc < %s -mtriple=i686-- -mattr=+x87,-sse2,-sse -global-isel -global-isel-abort=1 | FileCheck %s --check-prefixes=X86
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@RKSimon RKSimon Jun 11, 2025

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can we add f32/f64 test coverage here? otherwise we've lost all x87-only fabs tests

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@mahesh-attarde mahesh-attarde Jun 12, 2025

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This is known issue, we discussed it earlier while submitting test review.
#142558 (comment)

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@e-kud e-kud Jun 13, 2025

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We can store the value instead of returning.

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@mahesh-attarde mahesh-attarde Jun 19, 2025

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done


define x86_fp80 @test_x86_fp80_abs(x86_fp80 %arg) {
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@e-kud e-kud Jun 11, 2025

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Probably would be nice to see how we handle floats and double without SSE.

; X64-LABEL: test_x86_fp80_abs:
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66 changes: 55 additions & 11 deletions llvm/test/CodeGen/X86/isel-fabs.ll
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@@ -1,27 +1,43 @@
; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py UTC_ARGS: --version 5
; RUN: llc < %s -mtriple=x86_64-- -mattr=-x87 | FileCheck %s --check-prefixes=X64
; RUN: llc < %s -mtriple=x86_64-- -mattr=-x87 -fast-isel -fast-isel-abort=1 | FileCheck %s --check-prefixes=X64
; RUN: llc < %s -mtriple=i686-- -mattr=-x87 | FileCheck %s --check-prefixes=X86
; RUN: llc < %s -mtriple=i686-- -mattr=-x87 -fast-isel -fast-isel-abort=1 | FileCheck %s --check-prefixes=FASTISEL-X86

; RUN: llc < %s -mtriple=x86_64-- -mattr=-x87,+sse,+sse2 | FileCheck %s --check-prefixes=X64
; RUN: llc < %s -mtriple=x86_64-- -mattr=-x87,+sse,+sse2 -fast-isel -fast-isel-abort=1 | FileCheck %s --check-prefixes=X64
; RUN: llc < %s -mtriple=x86_64-- -mattr=-x87,+sse,+sse2 -global-isel -global-isel-abort=1 | FileCheck %s --check-prefixes=GISEL-X64
; RUN: llc < %s -mtriple=i686-- -mattr=-x87,+sse,+sse2 | FileCheck %s --check-prefixes=X86
; RUN: llc < %s -mtriple=i686-- -mattr=-x87,+sse,+sse2 -fast-isel -fast-isel-abort=1 | FileCheck %s --check-prefixes=FASTISEL-X86
; RUN: llc < %s -mtriple=i686-- -mattr=-x87,+sse,+sse2 -global-isel -global-isel-abort=1 | FileCheck %s --check-prefixes=GISEL-X86

define float @test_float_abs(float %arg) {
; X64-LABEL: test_float_abs:
; X64: # %bb.0:
; X64-NEXT: andps {{\.?LCPI[0-9]+_[0-9]+}}(%rip), %xmm0
; X64-NEXT: retq
;
; GISEL-X64-LABEL: test_float_abs:
; GISEL-X64: # %bb.0:
; GISEL-X64-NEXT: movd %xmm0, %eax
; GISEL-X64-NEXT: andl $2147483647, %eax # imm = 0x7FFFFFFF
; GISEL-X64-NEXT: movd %eax, %xmm0
; GISEL-X64-NEXT: retq
;
; X86-LABEL: test_float_abs:
; X86: # %bb.0:
; X86-NEXT: movl $2147483647, %eax # imm = 0x7FFFFFFF
; X86-NEXT: andl {{[0-9]+}}(%esp), %eax
; X86-NEXT: movd {{.*#+}} xmm0 = mem[0],zero,zero,zero
; X86-NEXT: pand {{\.?LCPI[0-9]+_[0-9]+}}, %xmm0
; X86-NEXT: movd %xmm0, %eax
; X86-NEXT: retl
;
; FASTISEL-X86-LABEL: test_float_abs:
; FASTISEL-X86: # %bb.0:
; FASTISEL-X86-NEXT: movl {{[0-9]+}}(%esp), %eax
; FASTISEL-X86-NEXT: andl $2147483647, %eax # imm = 0x7FFFFFFF
; FASTISEL-X86-NEXT: movd {{.*#+}} xmm0 = mem[0],zero,zero,zero
; FASTISEL-X86-NEXT: pand {{\.?LCPI[0-9]+_[0-9]+}}, %xmm0
; FASTISEL-X86-NEXT: movd %xmm0, %eax
; FASTISEL-X86-NEXT: retl
;
; GISEL-X86-LABEL: test_float_abs:
; GISEL-X86: # %bb.0:
; GISEL-X86-NEXT: movl $2147483647, %eax # imm = 0x7FFFFFFF
; GISEL-X86-NEXT: andl {{[0-9]+}}(%esp), %eax
; GISEL-X86-NEXT: retl
%abs = tail call float @llvm.fabs.f32(float %arg)
ret float %abs
}
Expand All @@ -32,6 +48,14 @@ define double @test_double_abs(double %arg) {
; X64-NEXT: andps {{\.?LCPI[0-9]+_[0-9]+}}(%rip), %xmm0
; X64-NEXT: retq
;
; GISEL-X64-LABEL: test_double_abs:
; GISEL-X64: # %bb.0:
; GISEL-X64-NEXT: movabsq $9223372036854775807, %rax # imm = 0x7FFFFFFFFFFFFFFF
; GISEL-X64-NEXT: movq %xmm0, %rcx
; GISEL-X64-NEXT: andq %rax, %rcx
; GISEL-X64-NEXT: movq %rcx, %xmm0
; GISEL-X64-NEXT: retq
;
; X86-LABEL: test_double_abs:
; X86: # %bb.0:
; X86-NEXT: movl {{[0-9]+}}(%esp), %eax
Expand All @@ -41,10 +65,30 @@ define double @test_double_abs(double %arg) {
;
; FASTISEL-X86-LABEL: test_double_abs:
; FASTISEL-X86: # %bb.0:
; FASTISEL-X86-NEXT: pushl %ebp
; FASTISEL-X86-NEXT: .cfi_def_cfa_offset 8
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@RKSimon RKSimon Jun 11, 2025

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add nounwind to get rid of the cfi noise

; FASTISEL-X86-NEXT: .cfi_offset %ebp, -8
; FASTISEL-X86-NEXT: movl %esp, %ebp
; FASTISEL-X86-NEXT: .cfi_def_cfa_register %ebp
; FASTISEL-X86-NEXT: andl $-8, %esp
; FASTISEL-X86-NEXT: subl $8, %esp
; FASTISEL-X86-NEXT: movsd {{.*#+}} xmm0 = mem[0],zero
; FASTISEL-X86-NEXT: andps {{\.?LCPI[0-9]+_[0-9]+}}, %xmm0
; FASTISEL-X86-NEXT: movlps %xmm0, (%esp)
; FASTISEL-X86-NEXT: movl (%esp), %eax
; FASTISEL-X86-NEXT: movl {{[0-9]+}}(%esp), %edx
; FASTISEL-X86-NEXT: movl {{[0-9]+}}(%esp), %eax
; FASTISEL-X86-NEXT: andl $2147483647, %edx # imm = 0x7FFFFFFF
; FASTISEL-X86-NEXT: movl %ebp, %esp
; FASTISEL-X86-NEXT: popl %ebp
; FASTISEL-X86-NEXT: .cfi_def_cfa %esp, 4
; FASTISEL-X86-NEXT: retl
;
; GISEL-X86-LABEL: test_double_abs:
; GISEL-X86: # %bb.0:
; GISEL-X86-NEXT: movl $-1, %eax
; GISEL-X86-NEXT: movl $2147483647, %edx # imm = 0x7FFFFFFF
; GISEL-X86-NEXT: andl {{[0-9]+}}(%esp), %eax
; GISEL-X86-NEXT: andl {{[0-9]+}}(%esp), %edx
; GISEL-X86-NEXT: retl
%abs = tail call double @llvm.fabs.f64(double %arg)
ret double %abs
}
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