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Merged
dkorpel merged 1 commit into from
Sep 23, 2026
Merged

Build compiler with PGO+LTO #748

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3 changes: 3 additions & 0 deletions changelog/pgo.dd
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Original file line number Diff line number Diff line change
@@ -0,0 +1,3 @@
More heavily optimized official compiler release binaries

The compiler is now built with profile-guided (except 32-bit Linux) and link-time optimizations.
49 changes: 28 additions & 21 deletions create_dmd_release/create_dmd_release.d
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Expand Up @@ -341,18 +341,6 @@ void buildAll(Bits bits, string branch)
const dmdEnv = ` "DMD=`~cloneDir~`/dmd/generated/`~osDirName~`/release/`~bitsStr~`/dmd`~exe~`"`;
const isRelease = " ENABLE_RELEASE=1";

// Enable lto for everything except FreeBSD - the generated dmd segfaults immediatly.
// OSX is disabled "temporarily" due to https://github.com/dlang/installer/actions/runs/12156929210/job/33901843249?pr=588#step:6:660
// wherein OSX with LTO timeTraceProfiler a TLS variable gets put into LTO layout which asserts out in ldc.
version (FreeBSD)
const ltoOption = " ENABLE_LTO=0";
else version (linux)
const ltoOption = " ENABLE_LTO=" ~ (is32 ? "0" : "1");
else version(OSX)
const ltoOption = " ENABLE_LTO=0";
else
const ltoOption = " ENABLE_LTO=1";

const latest = " LATEST="~branch;
// PIC libraries on amd64 for PIE-by-default distributions, see Bugzilla 16794
version (linux)
Expand All @@ -363,17 +351,36 @@ void buildAll(Bits bits, string branch)
// common make arguments
const makecmd = make~jobs~makeModel~dmdEnv~isRelease~latest;

info("Building DMD "~bitsDisplay);
changeDir(cloneDir~"/dmd");
run(msvcVars~makecmd~ltoOption~" HOST_DMD="~hostDMD~" dmd");
bool usePGO = true;
version (linux)
{
// the LDC Linux multilib package doesn't have any 32-bit compiler-rt libs
if (is32)
usePGO = false;
}

info("Building Druntime "~bitsDisplay);
changeDir(cloneDir~"/dmd/druntime");
run(msvcVars~makecmd~pic);
if (usePGO)
{
string pgoDflags;
version (OSX)
{
// As of September 2026 (with LDC v1.43), there are 15 warnings about profile
// mismatches ('function control flow change detected (hash mismatch)').
// No idea why on Mac only; don't treat them as errors.
// (Enabling LTO for the instrumented compiler reduces them to 4 warnings.)
pgoDflags = " HOST_DFLAGS=-wi";
}

info("Building Phobos "~bitsDisplay);
changeDir(cloneDir~"/phobos");
run(msvcVars~makecmd~pic);
info("Building PGO+LTO'd dmd "~bitsDisplay~", incl. Druntime and Phobos");
changeDir(cloneDir~"/dmd");
run(msvcVars~makecmd~pic~" HOST_DMD="~hostDMD~pgoDflags~" dmd-pgo");
}
else
{
info("Building LTO'd dmd "~bitsDisplay~", incl. Druntime and Phobos");
changeDir(cloneDir~"/dmd");
run(msvcVars~makecmd~pic~" HOST_DMD="~hostDMD~" ENABLE_LTO=1 all phobos");
}

// Build docs
if(!skipDocs)
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