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[libclc] Refine __clc_fp*_subnormals_supported and __clc_flush_denormal_if_not_supported #157633

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[libclc] Refine __clc_fp*_subnormals_supported and __clc_flush_denormal_if_not_supported #157633

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7e2d210
[libclc] Refine __clc_fp*_subnormals_supported and __clc_flush_denorm…
wenju-he Sep 9, 2025
96ec9dc
Apply suggestions from code review
wenju-he Sep 9, 2025
d52fcdb
use __builtin_elementwise_canonicalize
wenju-he Sep 9, 2025
4608f77
set -fdenormal-fp-math-f32=dynamic build flag globally
wenju-he Sep 9, 2025
3f665ce
rename __clc_flush_denormal_if_not_supportedto __clc_soft_flush_deno…
wenju-he Sep 10, 2025
7b290a2
delete clc_sw_fma
wenju-he Oct 3, 2025
3da9705
-fdenormal-fp-math-f32 -> -fdenormal-fp-math
wenju-he Oct 3, 2025
7d21a1a
remove -Xclang before -fdenormal-fp-math=dynamic
wenju-he Oct 3, 2025
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19 changes: 1 addition & 18 deletions libclc/CMakeLists.txt
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Original file line number Diff line number Diff line change
Expand Up @@ -41,8 +41,6 @@ set( LIBCLC_MIN_LLVM 3.9.0 )
set( LIBCLC_TARGETS_TO_BUILD "all"
CACHE STRING "Semicolon-separated list of libclc targets to build, or 'all'." )

option( ENABLE_RUNTIME_SUBNORMAL "Enable runtime linking of subnormal support." OFF )

option(
LIBCLC_USE_SPIRV_BACKEND "Build SPIR-V targets with the SPIR-V backend." OFF
)
Expand Down Expand Up @@ -231,19 +229,6 @@ set( tahiti_aliases pitcairn verde oland hainan bonaire kabini kaveri hawaii
configure_file( libclc.pc.in libclc.pc @ONLY )
install( FILES ${CMAKE_CURRENT_BINARY_DIR}/libclc.pc DESTINATION "${CMAKE_INSTALL_DATADIR}/pkgconfig" )

if( ENABLE_RUNTIME_SUBNORMAL )
foreach( file IN ITEMS subnormal_use_default subnormal_disable )
link_bc(
TARGET ${file}
INPUTS ${CMAKE_CURRENT_SOURCE_DIR}/opencl/lib/generic/${file}.ll
)
install(
FILES $<TARGET_PROPERTY:${file},TARGET_FILE>
DESTINATION "${CMAKE_INSTALL_DATADIR}/clc"
)
endforeach()
endif()

find_package( Python3 REQUIRED COMPONENTS Interpreter )
file( TO_CMAKE_PATH ${CMAKE_CURRENT_SOURCE_DIR}/utils/gen_convert.py script_loc )
add_custom_command(
Expand Down Expand Up @@ -371,9 +356,6 @@ foreach( t ${LIBCLC_TARGETS_TO_BUILD} )
list( APPEND opencl_gen_files clspv-convert.cl )
else()
list( APPEND opencl_gen_files convert.cl )
if ( NOT ENABLE_RUNTIME_SUBNORMAL )
list( APPEND opencl_lib_files opencl/lib/generic/subnormal_use_default.ll )
endif()
endif()
endif()

Expand Down Expand Up @@ -430,6 +412,7 @@ foreach( t ${LIBCLC_TARGETS_TO_BUILD} )
# Error on undefined macros
-Werror=undef
-fdiscard-value-names
-fdenormal-fp-math=dynamic
)

if( NOT "${cpu}" STREQUAL "" )
Expand Down
19 changes: 0 additions & 19 deletions libclc/clc/include/clc/internal/math/clc_sw_fma.h
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1 change: 0 additions & 1 deletion libclc/clc/include/clc/math/clc_subnormal_config.h
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Original file line number Diff line number Diff line change
Expand Up @@ -10,7 +10,6 @@

#include <clc/clcfunc.h>

_CLC_DECL bool __clc_subnormals_disabled();
_CLC_DECL bool __clc_fp16_subnormals_supported();
_CLC_DECL bool __clc_fp32_subnormals_supported();
_CLC_DECL bool __clc_fp64_subnormals_supported();
Expand Down
24 changes: 6 additions & 18 deletions libclc/clc/include/clc/math/math.h
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Expand Up @@ -11,7 +11,6 @@

#include <clc/clc_as_type.h>
#include <clc/clcfunc.h>
#include <clc/math/clc_subnormal_config.h>

#define SNAN 0x001
#define QNAN 0x002
Expand All @@ -24,15 +23,6 @@
#define PNOR 0x100
#define PINF 0x200

#if (defined __AMDGCN__ || defined __R600__) && !defined __HAS_FMAF__
#define __CLC_HAVE_HW_FMA32() (0)
#elif defined(CLC_SPIRV)
bool __attribute__((noinline)) __clc_runtime_has_hw_fma32(void);
#define __CLC_HAVE_HW_FMA32() __clc_runtime_has_hw_fma32()
#else
#define __CLC_HAVE_HW_FMA32() (1)
#endif

#define HAVE_BITALIGN() (0)
#define HAVE_FAST_FMA32() (0)

Expand Down Expand Up @@ -65,14 +55,12 @@ bool __attribute__((noinline)) __clc_runtime_has_hw_fma32(void);

#define LOG_MAGIC_NUM_SP32 (1 + NUMEXPBITS_SP32 - EXPBIAS_SP32)

_CLC_OVERLOAD _CLC_INLINE float __clc_flush_denormal_if_not_supported(float x) {
int ix = __clc_as_int(x);
if (!__clc_fp32_subnormals_supported() && ((ix & EXPBITS_SP32) == 0) &&
((ix & MANTBITS_SP32) != 0)) {
ix &= SIGNBIT_SP32;
x = __clc_as_float(ix);
}
return x;
_CLC_OVERLOAD _CLC_INLINE float __clc_soft_flush_denormal(float x) {
// Avoid calling __clc_fp32_subnormals_supported here: it uses
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You might have less trouble just using canonicalize for now and trying to relax it later

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You might have less trouble just using canonicalize for now and trying to relax it later

do you mean reverting __clc_soft_flush_denormal to use __clc_fp32_subnormals_supported which uses llvm.canonicalize, or just replacing use of __clc_fp32_subnormals_supported with __builtin_elementwise_canonicalize?

// llvm.canonicalize, which quiets sNaN.
return __builtin_elementwise_abs(x) < 0x1p-149f
? __builtin_elementwise_copysign(0.0f, x)
: x;
}

#ifdef cl_khr_fp64
Expand Down
1 change: 0 additions & 1 deletion libclc/clc/lib/clspv/SOURCES
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@@ -1,2 +1 @@
math/clc_sw_fma.cl
integer/clc_mul_hi.cl
274 changes: 0 additions & 274 deletions libclc/clc/lib/clspv/math/clc_sw_fma.cl
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