From cc64a0405ae0e4025f0b18be3bd0d813cb36fea0 Mon Sep 17 00:00:00 2001 From: "William L. DeRieux IV" Date: Tue, 28 Dec 2021 08:06:24 -0500 Subject: [PATCH] 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 --- CMakeLists.txt | 1 - src/CMakeLists.txt | 10 ++++++++++ 2 files changed, 10 insertions(+), 1 deletion(-) diff --git a/CMakeLists.txt b/CMakeLists.txt index ea212bede..3b4b9f4f5 100644 --- a/CMakeLists.txt +++ b/CMakeLists.txt @@ -286,7 +286,6 @@ endif() # Subdirectories # Be sure to add all relevant definitions above this - add_subdirectory(src) diff --git a/src/CMakeLists.txt b/src/CMakeLists.txt index 4803b475b..e3389cea9 100644 --- a/src/CMakeLists.txt +++ b/src/CMakeLists.txt @@ -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")