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bootstrap.c: work around the gcc sra miscomp using preprocessor checks rather than CLI arg (#31589)
Closes #31577 I've also extended the "good" ranges to fit versions >14.3 and >13.4, since both of these branches have the fix merged so if they ever make a dot release it should be good. Reviewed-on: https://codeberg.org/ziglang/zig/pulls/31589 Reviewed-by: Andrew Kelley <andrew@ziglang.org> Co-authored-by: fardragon <michaldrozd@protonmail.ch> Co-committed-by: fardragon <michaldrozd@protonmail.ch>
This commit is contained in:
fardragon
+16
-5
@@ -625,11 +625,22 @@ else()
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else()
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set(ZIG2_LINK_FLAGS "-Wl,-z,stack-size=0x10000000")
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endif()
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# Prevent GCC from miscompiling 'zig2.c'. See also 'workaround_gcc_sra_miscomp' in 'bootstrap.c'.
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if (CMAKE_C_COMPILER_ID STREQUAL "GNU" AND
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CMAKE_C_COMPILER_VERSION VERSION_GREATER_EQUAL "13.0" AND
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CMAKE_C_COMPILER_VERSION VERSION_LESS_EQUAL "15.2")
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set(ZIG2_COMPILE_FLAGS "${ZIG2_COMPILE_FLAGS} -fno-tree-sra")
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if (CMAKE_C_COMPILER_ID STREQUAL "GNU")
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# Prevent GCC from miscompiling 'zig2.c'. See also 'GCC_BUG_119085_PRESENT' workaround details in 'bootstrap.c'.
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if (
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(CMAKE_C_COMPILER_VERSION VERSION_GREATER_EQUAL "10.0" AND
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CMAKE_C_COMPILER_VERSION VERSION_LESS_EQUAL "13.4") OR
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(CMAKE_C_COMPILER_VERSION VERSION_GREATER_EQUAL "14.0" AND
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CMAKE_C_COMPILER_VERSION VERSION_LESS_EQUAL "14.3") OR
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(CMAKE_C_COMPILER_VERSION VERSION_GREATER_EQUAL "15.0" AND
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CMAKE_C_COMPILER_VERSION VERSION_LESS "15.2")
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)
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set(ZIG2_COMPILE_FLAGS "${ZIG2_COMPILE_FLAGS} -fno-tree-sra")
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endif()
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# Prevent GCC from spamming false positive `-Waddress-of-packed-member` warnings in 'zig2.c'.
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# See also 'GCC_BUG_94081_PRESENT' workaround details in 'bootstrap.c'.
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set(ZIG2_COMPILE_FLAGS "${ZIG2_COMPILE_FLAGS} -Wno-address-of-packed-member")
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endif()
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endif()
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+49
-21
@@ -13,6 +13,49 @@ static void panic(const char *reason) {
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abort();
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}
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#if defined(__GNUC__) && !defined(__clang__)
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#define GCC_VERSION (__GNUC__ * 10000 \
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+ __GNUC_MINOR__ * 100 \
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+ __GNUC_PATCHLEVEL__)
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// GCC versions 10.0--15.1 have a miscompilation where some bytes of a union may get clobbered
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// depending on the union layout and the order in which types are defined. This miscompilation
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// affects the output of the C backend, and thus can affect the bootstrap process. Specifically,
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// we observe that using the self-hosted x86_64 backend in 'zig2' will cause all function calls
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// to be relocated incorrectly, causing immediate crashes on any binary produced by it.
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//
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// The only reliable workaround for this bug is to disable the optimization pass containing it,
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// so here we detect whether the compiler being used requires that workaround.
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//
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// The upstream bug is fixed in GCC version 15.2 onwards (and was also backported to the 13 and
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// 14 branches, however there are no 13.x and 14.x releases that contains the fix as of now).
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// Once this bug is no longer widespread, we can remove this workaround.
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//
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// Upstream bug report: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=119085
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#if (GCC_VERSION >= 160000) || \
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(GCC_VERSION >= 150200 && GCC_VERSION < 160000) || \
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(GCC_VERSION > 140300 && GCC_VERSION < 150000) || \
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(GCC_VERSION > 130400 && GCC_VERSION < 140000) || \
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(GCC_VERSION <= 100000)
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#define GCC_BUG_119085_PRESENT 0
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#else
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#define GCC_BUG_119085_PRESENT 1
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#endif
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// GCC doesn't take into account alignment annotations when --Waddress-of-packed-member is
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// evaluated, which causes false positive warnings when the C backend generates code that takes
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// the address of a field in a packed struct.
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//
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// There is no fix for this as now, so the only way to get rid of the false positive warnings
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// is to disable the flag altogether.
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//
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// Upstream bug report: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94081
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#define GCC_BUG_94081_PRESENT 1
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#else
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#define GCC_BUG_94081_PRESENT 0
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#define GCC_BUG_119085_PRESENT 0
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#endif
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#if defined(__WIN32__)
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#error TODO write the functionality for executing child process into this build script
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#else
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@@ -102,26 +145,6 @@ int main(int argc, char **argv) {
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const char *cc = get_c_compiler();
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const char *host_triple = get_host_triple();
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// GCC versions 10.0--15.1 have a miscompilation where some bytes of a union may get clobbered
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// depending on the union layout and the order in which types are defined. This miscompilation
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// affects the output of the C backend, and thus can affect the bootstrap process. Specifically,
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// we observe that using the self-hosted x86_64 backend in 'zig2' will cause all function calls
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// to be relocated incorrectly, causing immediate crashes on any binary produced by it.
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//
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// The only reliable workaround for this bug is to disable the optimization pass containing it,
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// so here we check for a CLI flag requesting that workaround.
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//
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// The upstream bug is fixed in GCC version 15.2 onwards (and was also backported to the 13 and
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// 14 branches). Once this bug is no longer widespread, we can remove this CLI flag.
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//
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// Upstream bug report: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=119085
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bool workaround_gcc_sra_miscomp = false;
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for (int i = 1; i < argc; ++i) {
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if (!strcmp(argv[i], "--workaround-gcc-sra-miscomp")) {
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workaround_gcc_sra_miscomp = true;
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}
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}
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{
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const char *child_argv[] = {
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cc, "-o", "zig-wasm2c", "stage1/wasm2c.c", "-O2", "-std=c99", NULL,
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@@ -214,7 +237,12 @@ int main(int argc, char **argv) {
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"-pthread",
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#endif
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"-fno-strict-aliasing",
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workaround_gcc_sra_miscomp ? "-fno-tree-sra" : NULL,
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#if GCC_BUG_119085_PRESENT
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"-fno-tree-sra",
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#endif
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#if GCC_BUG_94081_PRESENT
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"-Wno-address-of-packed-member",
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#endif
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NULL,
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};
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print_and_run(child_argv);
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@@ -21,8 +21,7 @@ export ZIG_LOCAL_CACHE_DIR="$PWD/zig-local-cache"
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# Test building from source without LLVM.
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cc -o bootstrap bootstrap.c
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# See comments in bootstrap.c for an explanation of the flag given here.
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./bootstrap --workaround-gcc-sra-miscomp
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./bootstrap
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./zig2 build -Dno-lib
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./zig-out/bin/zig test test/behavior.zig
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