Enable ICF on Linux by MichalPetryka · Pull Request #129762 · dotnet/runtime

MichalPetryka · 2026-06-23T18:15:17Z

CI is green and it saves on average 2% in size.

Opening to see CI results and size diffs

MichalPetryka · 2026-06-24T05:38:49Z

@am11 Since I think you worked in this area the most, what do you think about this? It seems that the GCC build job failed cause ld does not support the flag.

Do the official builds use lld instead? If not, it probably doesn't make sense to do any checking for linker here.

Also, it seems like NativeAOT doesn't use the flags from here.

Co-authored-by: Adeel Mujahid <3840695+am11@users.noreply.github.com>

am11 · 2026-06-24T08:17:14Z

@MichalStrehovsky, experimented with it earlier. We may need changes from #87045.

MichalPetryka · 2026-06-24T08:19:18Z

@MichalStrehovsky, experimented with it earlier. We may need changes from #87045.

My intent here was to only enable it for native code in the runtime, I'd leave the handling of NAOT outputs to @MichalStrehovsky.

am11 · 2026-06-24T08:23:39Z

Do you see any size difference before/after on linux?

$ ./build.sh clr+libs -c Release
$ find artifacts/bin/coreclr/linux.x64.Release -name '*.so*' -exec du -sh {} \;

MichalPetryka · 2026-06-24T08:27:50Z

Do you see any size difference before/after on linux?
$ ./build.sh clr+libs -c Release
$ find artifacts/bin/coreclr/linux.x64.Release -name '*.so*' -exec du -sh {} \;

I currently do not have a Linux machine on hand to test it, that's why I wanted to see how it impacts rt-sz.

am11 · 2026-06-24T09:00:49Z

Before (bytes)	After (bytes)	Diff (bytes)	Diff %	Path
`2804824`	`2746264`	`-58560`	`-2.09%`	artifacts/bin/coreclr/linux.arm64.Release/libclrjit_universal_arm64_arm64.so
`1425720`	`1295560`	`-130160`	`-9.13%`	artifacts/bin/coreclr/linux.arm64.Release/sharedFramework/libmscordbi.so
`1765712`	`1723664`	`-42048`	`-2.38%`	artifacts/bin/coreclr/linux.arm64.Release/sharedFramework/libmscordaccore.so
`3542448`	`3529920`	`-12528`	`-0.35%`	artifacts/bin/coreclr/linux.arm64.Release/sharedFramework/libclrjit.so
`64148184`	`64237208`	`+89024`	`+0.14%`	artifacts/bin/coreclr/linux.arm64.Release/sharedFramework/libmscordaccore.so.dbg
`648744`	`540616`	`-108128`	`-16.67%`	artifacts/bin/coreclr/linux.arm64.Release/sharedFramework/libcoreclrtraceptprovider.so
`4085928`	`4140104`	`+54176`	`+1.33%`	artifacts/bin/coreclr/linux.arm64.Release/sharedFramework/libclrgcexp.so.dbg
`756904`	`745544`	`-11360`	`-1.50%`	artifacts/bin/coreclr/linux.arm64.Release/sharedFramework/libclrgcexp.so
`19504344`	`19491816`	`-12528`	`-0.06%`	artifacts/bin/coreclr/linux.arm64.Release/sharedFramework/libclrjit.so.dbg
`13660760`	`13661672`	`+912`	`+0.01%`	artifacts/bin/coreclr/linux.arm64.Release/sharedFramework/libmscordbi.so.dbg
`5819656`	`5801704`	`-17952`	`-0.31%`	artifacts/bin/coreclr/linux.arm64.Release/sharedFramework/libclrgc.so.dbg
`5307896`	`5216440`	`-91456`	`-1.72%`	artifacts/bin/coreclr/linux.arm64.Release/sharedFramework/libcoreclr.so
`714296`	`696344`	`-17952`	`-2.51%`	artifacts/bin/coreclr/linux.arm64.Release/sharedFramework/libclrgc.so
`125775536`	`125815144`	`+39608`	`+0.03%`	artifacts/bin/coreclr/linux.arm64.Release/sharedFramework/libcoreclr.so.dbg
`1636728`	`1594136`	`-42592`	`-2.60%`	artifacts/bin/coreclr/linux.arm64.Release/sharedFramework/libcoreclrtraceptprovider.so.dbg
`1425720`	`1295560`	`-130160`	`-9.13%`	artifacts/bin/coreclr/linux.arm64.Release/libmscordbi.so
`2762576`	`2703024`	`-59552`	`-2.16%`	artifacts/bin/coreclr/linux.arm64.Release/libclrjit_win_x86_arm64.so
`46593576`	`46598952`	`+5376`	`+0.01%`	artifacts/bin/coreclr/linux.arm64.Release/libclrjit_win_x64_arm64.so.dbg
`1765712`	`1723664`	`-42048`	`-2.38%`	artifacts/bin/coreclr/linux.arm64.Release/libmscordaccore.so
`4252864`	`4284640`	`+31776`	`+0.75%`	artifacts/bin/coreclr/linux.arm64.Release/libsuperpmi-shim-collector.so.dbg
`4190536`	`4189608`	`-928`	`-0.02%`	artifacts/bin/coreclr/linux.arm64.Release/libsuperpmi-shim-counter.so.dbg
`2804824`	`2746264`	`-58560`	`-2.09%`	artifacts/bin/coreclr/linux.arm64.Release/crossgen2-published/libclrjit_universal_arm64_arm64.so
`2762576`	`2703024`	`-59552`	`-2.16%`	artifacts/bin/coreclr/linux.arm64.Release/crossgen2-published/libclrjit_win_x86_arm64.so
`2117088`	`2066624`	`-50464`	`-2.38%`	artifacts/bin/coreclr/linux.arm64.Release/crossgen2-published/libclrjit_universal_arm_arm64.so
`49392`	`49312`	`-80`	`-0.16%`	artifacts/bin/coreclr/linux.arm64.Release/crossgen2-published/libjitinterface_arm64.so
`2849224`	`2789064`	`-60160`	`-2.11%`	artifacts/bin/coreclr/linux.arm64.Release/crossgen2-published/libclrjit_win_x64_arm64.so
`2870784`	`2809472`	`-61312`	`-2.14%`	artifacts/bin/coreclr/linux.arm64.Release/crossgen2-published/libclrjit_unix_x64_arm64.so
`2027688`	`1973160`	`-54528`	`-2.69%`	artifacts/bin/coreclr/linux.arm64.Release/crossgen2-published/libclrjit_universal_wasm_arm64.so
`3542448`	`3529920`	`-12528`	`-0.35%`	artifacts/bin/coreclr/linux.arm64.Release/libclrjit.so
`48364656`	`48437168`	`+72512`	`+0.15%`	artifacts/bin/coreclr/linux.arm64.Release/libclrjit_universal_arm64_arm64.so.dbg
`64148184`	`64237208`	`+89024`	`+0.14%`	artifacts/bin/coreclr/linux.arm64.Release/libmscordaccore.so.dbg
`319464`	`318312`	`-1152`	`-0.36%`	artifacts/bin/coreclr/linux.arm64.Release/libsuperpmi-shim-simple.so
`2117088`	`2066624`	`-50464`	`-2.38%`	artifacts/bin/coreclr/linux.arm64.Release/libclrjit_universal_arm_arm64.so
`648744`	`540616`	`-108128`	`-16.67%`	artifacts/bin/coreclr/linux.arm64.Release/libcoreclrtraceptprovider.so
`4085928`	`4140104`	`+54176`	`+1.33%`	artifacts/bin/coreclr/linux.arm64.Release/libclrgcexp.so.dbg
`46724656`	`46794416`	`+69760`	`+0.15%`	artifacts/bin/coreclr/linux.arm64.Release/libclrjit_unix_x64_arm64.so.dbg
`49392`	`49312`	`-80`	`-0.16%`	artifacts/bin/coreclr/linux.arm64.Release/libjitinterface_arm64.so
`756904`	`745544`	`-11360`	`-1.50%`	artifacts/bin/coreclr/linux.arm64.Release/libclrgcexp.so
`19504344`	`19491816`	`-12528`	`-0.06%`	artifacts/bin/coreclr/linux.arm64.Release/libclrjit.so.dbg
`3971744`	`3970592`	`-1152`	`-0.03%`	artifacts/bin/coreclr/linux.arm64.Release/libsuperpmi-shim-simple.so.dbg
`13660760`	`13661672`	`+912`	`+0.01%`	artifacts/bin/coreclr/linux.arm64.Release/libmscordbi.so.dbg
`5819656`	`5801704`	`-17952`	`-0.31%`	artifacts/bin/coreclr/linux.arm64.Release/libclrgc.so.dbg
`2849224`	`2789064`	`-60160`	`-2.11%`	artifacts/bin/coreclr/linux.arm64.Release/libclrjit_win_x64_arm64.so
`2870784`	`2809472`	`-61312`	`-2.14%`	artifacts/bin/coreclr/linux.arm64.Release/libclrjit_unix_x64_arm64.so
`38333424`	`38348496`	`+15072`	`+0.04%`	artifacts/bin/coreclr/linux.arm64.Release/libclrjit_universal_arm_arm64.so.dbg
`46541744`	`46547728`	`+5984`	`+0.01%`	artifacts/bin/coreclr/linux.arm64.Release/libclrjit_win_x86_arm64.so.dbg
`2804824`	`2746264`	`-58560`	`-2.09%`	artifacts/bin/coreclr/linux.arm64.Release/crossgen2/libclrjit_universal_arm64_arm64.so
`2762576`	`2703024`	`-59552`	`-2.16%`	artifacts/bin/coreclr/linux.arm64.Release/crossgen2/libclrjit_win_x86_arm64.so
`2117088`	`2066624`	`-50464`	`-2.38%`	artifacts/bin/coreclr/linux.arm64.Release/crossgen2/libclrjit_universal_arm_arm64.so
`49392`	`49312`	`-80`	`-0.16%`	artifacts/bin/coreclr/linux.arm64.Release/crossgen2/libjitinterface_arm64.so
`2849224`	`2789064`	`-60160`	`-2.11%`	artifacts/bin/coreclr/linux.arm64.Release/crossgen2/libclrjit_win_x64_arm64.so
`2870784`	`2809472`	`-61312`	`-2.14%`	artifacts/bin/coreclr/linux.arm64.Release/crossgen2/libclrjit_unix_x64_arm64.so
`2027688`	`1973160`	`-54528`	`-2.69%`	artifacts/bin/coreclr/linux.arm64.Release/crossgen2/libclrjit_universal_wasm_arm64.so
`352648`	`351720`	`-928`	`-0.26%`	artifacts/bin/coreclr/linux.arm64.Release/libsuperpmi-shim-counter.so
`5307896`	`5216440`	`-91456`	`-1.72%`	artifacts/bin/coreclr/linux.arm64.Release/libcoreclr.so
`15953352`	`15953352`	`+0`	`+0.00%`	artifacts/bin/coreclr/linux.arm64.Release/R2RDump/libcoredistools.so
`714296`	`696344`	`-17952`	`-2.51%`	artifacts/bin/coreclr/linux.arm64.Release/libclrgc.so
`382832`	`349072`	`-33760`	`-8.82%`	artifacts/bin/coreclr/linux.arm64.Release/libsuperpmi-shim-collector.so
`2027688`	`1973160`	`-54528`	`-2.69%`	artifacts/bin/coreclr/linux.arm64.Release/libclrjit_universal_wasm_arm64.so
`278832`	`278752`	`-80`	`-0.03%`	artifacts/bin/coreclr/linux.arm64.Release/libjitinterface_arm64.so.dbg
`125775536`	`125815144`	`+39608`	`+0.03%`	artifacts/bin/coreclr/linux.arm64.Release/libcoreclr.so.dbg
`316056`	`316056`	`+0`	`+0.00%`	artifacts/bin/coreclr/linux.arm64.Release/SuperFileCheck/runtimes/linux-arm64/native/libc++abi.so.1
`1469280`	`1469280`	`+0`	`+0.00%`	artifacts/bin/coreclr/linux.arm64.Release/SuperFileCheck/runtimes/linux-arm64/native/libc++.so.1
`1636728`	`1594136`	`-42592`	`-2.60%`	artifacts/bin/coreclr/linux.arm64.Release/libcoreclrtraceptprovider.so.dbg
`2804824`	`2746264`	`-58560`	`-2.09%`	artifacts/bin/coreclr/linux.arm64.Release/arm64/crossgen2/libclrjit_universal_arm64_arm64.so
`2762576`	`2703024`	`-59552`	`-2.16%`	artifacts/bin/coreclr/linux.arm64.Release/arm64/crossgen2/libclrjit_win_x86_arm64.so
`2117088`	`2066624`	`-50464`	`-2.38%`	artifacts/bin/coreclr/linux.arm64.Release/arm64/crossgen2/libclrjit_universal_arm_arm64.so
`49392`	`49312`	`-80`	`-0.16%`	artifacts/bin/coreclr/linux.arm64.Release/arm64/crossgen2/libjitinterface_arm64.so
`2849224`	`2789064`	`-60160`	`-2.11%`	artifacts/bin/coreclr/linux.arm64.Release/arm64/crossgen2/libclrjit_win_x64_arm64.so
`2870784`	`2809472`	`-61312`	`-2.14%`	artifacts/bin/coreclr/linux.arm64.Release/arm64/crossgen2/libclrjit_unix_x64_arm64.so
`2027688`	`1973160`	`-54528`	`-2.69%`	artifacts/bin/coreclr/linux.arm64.Release/arm64/crossgen2/libclrjit_universal_wasm_arm64.so
`2804824`	`2746264`	`-58560`	`-2.09%`	artifacts/bin/coreclr/linux.arm64.Release/arm64/ilc/libclrjit_universal_arm64_arm64.so
`2762576`	`2703024`	`-59552`	`-2.16%`	artifacts/bin/coreclr/linux.arm64.Release/arm64/ilc/libclrjit_win_x86_arm64.so
`2117088`	`2066624`	`-50464`	`-2.38%`	artifacts/bin/coreclr/linux.arm64.Release/arm64/ilc/libclrjit_universal_arm_arm64.so
`49392`	`49312`	`-80`	`-0.16%`	artifacts/bin/coreclr/linux.arm64.Release/arm64/ilc/libjitinterface_arm64.so
`2849224`	`2789064`	`-60160`	`-2.11%`	artifacts/bin/coreclr/linux.arm64.Release/arm64/ilc/libclrjit_win_x64_arm64.so
`2870784`	`2809472`	`-61312`	`-2.14%`	artifacts/bin/coreclr/linux.arm64.Release/arm64/ilc/libclrjit_unix_x64_arm64.so
`2027688`	`1973160`	`-54528`	`-2.69%`	artifacts/bin/coreclr/linux.arm64.Release/arm64/ilc/libclrjit_universal_wasm_arm64.so
`38873968`	`38950512`	`+76544`	`+0.20%`	artifacts/bin/coreclr/linux.arm64.Release/libclrjit_universal_wasm_arm64.so.dbg
`2804824`	`2746264`	`-58560`	`-2.09%`	artifacts/bin/coreclr/linux.arm64.Release/ilc-published/libclrjit_universal_arm64_arm64.so
`2762576`	`2703024`	`-59552`	`-2.16%`	artifacts/bin/coreclr/linux.arm64.Release/ilc-published/libclrjit_win_x86_arm64.so
`2117088`	`2066624`	`-50464`	`-2.38%`	artifacts/bin/coreclr/linux.arm64.Release/ilc-published/libclrjit_universal_arm_arm64.so
`49392`	`49312`	`-80`	`-0.16%`	artifacts/bin/coreclr/linux.arm64.Release/ilc-published/libjitinterface_arm64.so
`2849224`	`2789064`	`-60160`	`-2.11%`	artifacts/bin/coreclr/linux.arm64.Release/ilc-published/libclrjit_win_x64_arm64.so
`2870784`	`2809472`	`-61312`	`-2.14%`	artifacts/bin/coreclr/linux.arm64.Release/ilc-published/libclrjit_unix_x64_arm64.so
`2027688`	`1973160`	`-54528`	`-2.69%`	artifacts/bin/coreclr/linux.arm64.Release/ilc-published/libclrjit_universal_wasm_arm64.so
`2804824`	`2746264`	`-58560`	`-2.09%`	artifacts/bin/coreclr/linux.arm64.Release/ilc/libclrjit_universal_arm64_arm64.so
`2762576`	`2703024`	`-59552`	`-2.16%`	artifacts/bin/coreclr/linux.arm64.Release/ilc/libclrjit_win_x86_arm64.so
`2117088`	`2066624`	`-50464`	`-2.38%`	artifacts/bin/coreclr/linux.arm64.Release/ilc/libclrjit_universal_arm_arm64.so
`49392`	`49312`	`-80`	`-0.16%`	artifacts/bin/coreclr/linux.arm64.Release/ilc/libjitinterface_arm64.so
`2849224`	`2789064`	`-60160`	`-2.11%`	artifacts/bin/coreclr/linux.arm64.Release/ilc/libclrjit_win_x64_arm64.so
`2870784`	`2809472`	`-61312`	`-2.14%`	artifacts/bin/coreclr/linux.arm64.Release/ilc/libclrjit_unix_x64_arm64.so
`2027688`	`1973160`	`-54528`	`-2.69%`	artifacts/bin/coreclr/linux.arm64.Release/ilc/libclrjit_universal_wasm_arm64.so
`106664`	`103208`	`-3456`	`-3.24%`	artifacts/bin/native/net11.0-linux-Release-arm64/libSystem.Native.so
`3625816`	`3622568`	`-3248`	`-0.09%`	artifacts/bin/native/net11.0-linux-Release-arm64/libSystem.IO.Compression.Native.so.dbg
`42088`	`42088`	`+0`	`+0.00%`	artifacts/bin/native/net11.0-linux-Release-arm64/libSystem.IO.Ports.Native.so.dbg
`14064`	`14064`	`+0`	`+0.00%`	artifacts/bin/native/net11.0-linux-Release-arm64/libSystem.IO.Ports.Native.so
`574672`	`573520`	`-1152`	`-0.20%`	artifacts/bin/native/net11.0-linux-Release-arm64/libSystem.Security.Cryptography.Native.OpenSsl.so.dbg
`1369216`	`1365968`	`-3248`	`-0.24%`	artifacts/bin/native/net11.0-linux-Release-arm64/libSystem.IO.Compression.Native.so
`238032`	`238032`	`+0`	`+0.00%`	artifacts/bin/native/net11.0-linux-Release-arm64/libSystem.Globalization.Native.so.dbg
`395408`	`391952`	`-3456`	`-0.87%`	artifacts/bin/native/net11.0-linux-Release-arm64/libSystem.Native.so.dbg
`237544`	`236392`	`-1152`	`-0.48%`	artifacts/bin/native/net11.0-linux-Release-arm64/libSystem.Security.Cryptography.Native.OpenSsl.so
`64832`	`64832`	`+0`	`+0.00%`	artifacts/bin/native/net11.0-linux-Release-arm64/libSystem.Globalization.Native.so
`42344`	`42344`	`+0`	`+0.00%`	artifacts/bin/native/net11.0-linux-Release-arm64/libSystem.Net.Security.Native.so.dbg
`15280`	`15280`	`+0`	`+0.00%`	artifacts/bin/native/net11.0-linux-Release-arm64/libSystem.Net.Security.Native.so
`909602336`	`906807088`	`-2795248`	`-0.31%`	TOTAL

MichalPetryka · 2026-06-24T09:06:08Z

@am11 Can you show the total without .dbg files?

Also, it seems like emscripten doesn't support icf even with lld, what's the proper condition for excluding that?

Co-authored-by: Adeel Mujahid <3840695+am11@users.noreply.github.com>

am11 · 2026-06-24T09:18:23Z

@am11 Can you show the total without .dbg files?

| 157295704 | 154012152 | -3283552 | -2.09% | TOTAL |

am11 · 2026-06-24T09:22:07Z

captured befroe.md and after.md with this:

echo "| Size (human) | Size (bytes) | Path |"; find artifacts/bin/coreclr/linux.arm64.Release artifacts/bin/native/net11.0-linux-Release-arm64 -name '*.so*' | xargs -I{} bash -c 'echo "| $(du -sh "$0" | cut -f1) | $(du -sb "$0" | cut -f1) | $0 |"' {}

then asked AI to compute deltas (which used python script).

dotnet-policy-service · 2026-06-24T12:57:11Z

Tagging subscribers to this area: @dotnet/runtime-infrastructure
See info in area-owners.md if you want to be subscribed.

Try enabling ICF on Linux

80202e3

Opening to see CI results and size diffs

github-actions Bot added the area-NativeAOT-coreclr label Jun 23, 2026

dotnet-policy-service Bot added the community-contribution Indicates that the PR has been added by a community member label Jun 23, 2026

github-actions Bot mentioned this pull request Jun 23, 2026

129762 MichalStrehovsky/rt-sz#233

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am11 reviewed Jun 24, 2026

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Comment thread eng/native/configurecompiler.cmake Outdated

Update eng/native/configurecompiler.cmake

d6cf672

Co-authored-by: Adeel Mujahid <3840695+am11@users.noreply.github.com>

am11 added area-Infrastructure-coreclr Only use for closed issues and removed area-NativeAOT-coreclr labels Jun 24, 2026

github-project-automation Bot added this to Runtime Infra Jun 24, 2026

MichalPetryka added 2 commits June 24, 2026 10:24

Also enable for NativeAOT

46f3dcb

Fix accidental file corruption

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github-actions Bot mentioned this pull request Jun 24, 2026

129762 MichalStrehovsky/rt-sz#234

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am11 reviewed Jun 24, 2026

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Comment thread eng/native/configurecompiler.cmake Outdated

Update eng/native/configurecompiler.cmake

c33eafe

Co-authored-by: Adeel Mujahid <3840695+am11@users.noreply.github.com>

MichalPetryka marked this pull request as ready for review June 24, 2026 09:22

MichalPetryka requested a review from MichalStrehovsky as a code owner June 24, 2026 09:22

MichalPetryka changed the title ~~Try enabling ICF on Linux~~ Enable ICF on Linux Jun 24, 2026

This was referenced Jun 24, 2026

slow macOS - "##[error]The job running on agent Azure Pipelines 9 ran longer than the maximum time of 60 minutes." dotnet/dnceng#1883

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The Operation will be canceled. The next steps may not contain expected logs. dotnet/dnceng#3008

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Enable ICF on Linux#129762

Enable ICF on Linux#129762
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MichalPetryka commented Jun 23, 2026 •

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