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Automatically use SSE registers for FP operations on i386 (#11853)
use SSE for floating-point operations to avoid issues with improper fp-rounding and
loss of precision when moving fp-data to incompatible or less-precise
registers/storage locations

https://gcc.gnu.org/wiki/FloatingPointMath
https://gcc.gnu.org/wiki/x87note
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neoh4x0r committed Dec 28, 2021
1 parent 7f6306c commit cc64a0405ae0e4025f0b18be3bd0d813cb36fea0
Showing with 10 additions and 1 deletion.
  1. +0 −1 CMakeLists.txt
  2. +10 −0 src/CMakeLists.txt
@@ -286,7 +286,6 @@ endif()

# Subdirectories
# Be sure to add all relevant definitions above this

add_subdirectory(src)


@@ -769,6 +769,16 @@ else()
# - we don't deal with Inf/NaN or signed zero
set(MATH_FLAGS "-fno-math-errno -fno-trapping-math -ffinite-math-only -fno-signed-zeros")

# Enable SSE for floating point math on 32-bit x86 by default
# reasoning see minetest issue #11810 and https://gcc.gnu.org/wiki/FloatingPointMath
if(CMAKE_SIZEOF_VOID_P EQUAL 4)
check_c_source_compiles("#ifndef __i686__\n#error\n#endif\nint main(){}" IS_I686)
if(IS_I686)
message(STATUS "Detected Intel x86: using SSE instead of x87 FPU")
set(OTHER_FLAGS "${OTHER_FLAGS} -mfpmath=sse -msse")
endif()
endif()

set(CMAKE_CXX_FLAGS_RELEASE "-DNDEBUG ${RELEASE_WARNING_FLAGS} ${WARNING_FLAGS} ${OTHER_FLAGS} -Wall -pipe -funroll-loops")
if(CMAKE_SYSTEM_NAME MATCHES "(Darwin|BSD|DragonFly)")
set(CMAKE_CXX_FLAGS_RELEASE "${CMAKE_CXX_FLAGS_RELEASE} -Os")

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