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Better guard release only compiler flags #2395

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Merged
jviotti merged 2 commits into from
May 21, 2026
Merged

Better guard release only compiler flags #2395

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c2281a7
Better guard release only compiler flags
jviotti May 21, 2026
c3d0491
Fix
jviotti May 21, 2026
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38 changes: 27 additions & 11 deletions cmake/common/compiler/options.cmake
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Original file line number Diff line number Diff line change
@@ -1,3 +1,13 @@
# Applies the shared compiler defaults to <target> at <visibility>.
#
# Flag categories handled here:
# - Diagnostics (-W...): always on, every config
# - Language semantics (-fwrapv, -fstrict-aliasing, -fno-rtti on GCC): always on
# - Optimization-related (loop unrolling, vectorization, fast-math relaxations):
# gated to non-Debug configs because they have no effect at -O0 but still
# cost Clang/GCC pipeline time
#
# Do not add optimization-only flags here without a generator-expression gate
function(sourcemeta_add_default_options visibility target)
if(SOURCEMETA_COMPILER_MSVC)
# See https://learn.microsoft.com/en-us/cpp/build/reference/compiler-options-listed-by-category
Expand Down Expand Up @@ -40,22 +50,28 @@ function(sourcemeta_add_default_options visibility target)
$<$<OR:$<COMPILE_LANGUAGE:CXX>,$<COMPILE_LANGUAGE:OBJCXX>>:-Wnon-virtual-dtor>
$<$<OR:$<COMPILE_LANGUAGE:CXX>,$<COMPILE_LANGUAGE:OBJCXX>>:-Woverloaded-virtual>
$<$<OR:$<COMPILE_LANGUAGE:CXX>,$<COMPILE_LANGUAGE:OBJCXX>>:-Winvalid-offsetof>
-funroll-loops
# Semantics, not optimization: keep on for every config
-fstrict-aliasing
-ftree-vectorize

# To improve how much GCC/Clang will vectorize
# Assume that signed arithmetic overflow of addition, subtraction and
# multiplication wraps around using twos-complement representation
# See https://users.cs.utah.edu/~regehr/papers/overflow12.pdf
# See https://www.postgresql.org/message-id/1689.1134422394@sss.pgh.pa.us
-fwrapv
# Fast-math relaxations relax IEEE conformance (errno after math.h,
# signed-zero handling, reassociation), so they affect observable
# behavior and must apply to every config to keep Debug and Release
# semantics aligned
-fno-math-errno
-fno-trapping-math
-fno-signed-zeros
-freciprocal-math
-fassociative-math

# Assume that signed arithmetic overflow of addition, subtraction and
# multiplication wraps around using twos-complement representation
# See https://users.cs.utah.edu/~regehr/papers/overflow12.pdf
# See https://www.postgresql.org/message-id/1689.1134422394@sss.pgh.pa.us
-fwrapv)
# Optimization-only: emitted only when not building Debug. At -O0 these
# run analyses that never reach codegen, costing build time for no
# behavioral effect
$<$<NOT:$<CONFIG:Debug>>:-funroll-loops>
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@augmentcode augmentcode Bot May 21, 2026 •
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$<$<NOT:$<CONFIG:Debug>>:...> will also enable these flags when the build configuration is empty/unspecified (e.g., single-config generators if CMAKE_BUILD_TYPE isn’t set), which may defeat the intent of avoiding extra work at -O0. Consider explicitly handling the empty-config case or documenting that a build type must be set for this gating to behave as expected.

Severity: medium

Other Locations
  • cmake/common/compiler/options.cmake:65
  • cmake/common/compiler/options.cmake:68
  • cmake/common/compiler/options.cmake:69
  • cmake/common/compiler/options.cmake:70
  • cmake/common/compiler/options.cmake:71
  • cmake/common/compiler/options.cmake:72
  • cmake/common/compiler/options.cmake:98
  • cmake/common/compiler/options.cmake:100

Fix This in Augment

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$<$<NOT:$<CONFIG:Debug>>:-ftree-vectorize>)
endif()

if(SOURCEMETA_COMPILER_LLVM)
Expand All @@ -81,9 +97,9 @@ function(sourcemeta_add_default_options visibility target)
-Wrange-loop-analysis

# Enable loop vectorization for performance reasons
-fvectorize
$<$<NOT:$<CONFIG:Debug>>:-fvectorize>
# Enable vectorization of straight-line code for performance
-fslp-vectorize)
$<$<NOT:$<CONFIG:Debug>>:-fslp-vectorize>)
elseif(SOURCEMETA_COMPILER_GCC)
target_compile_options("${target}" ${visibility}
# Newer versions of GCC (i.e. 14) seem to print a lot of false-positives here
Expand Down
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