Gvn primitive

[cjgillot]

GVN separates MIR constants into deterministic and non-deterministic constants.

This was mainly useful because of ConstValue::Slice that generated an extra AllocId each time it appeared in the MIR. That variant has been removed.

The second use case was constants holding provenance: an AllocId could refer to different addresses depending on the crate doing the codegen.

This PR proposes to consider all constants of primitive type to be deterministic. If a constant of primitive type passes validation, then it does not contain provenance, so we have no risk of having an AllocId becoming different pointers.

r? @ghost for perf

[cjgillot]

@bors try @rust-timer queue

[rust-log-analyzer]

The job aarch64-gnu-llvm-20-1 failed! Check out the build log: (web) (plain enhanced) (plain)

Click to see the possible cause of the failure (guessed by this bot)

---- [incremental] tests/incremental/hashes/enum_constructors.rs stdout ----
------rustc stdout------------------------------

------rustc stderr------------------------------
{"$message_type":"diagnostic","message":"`optimized_mir(change_field_order_struct_like)` should be dirty but is not","code":null,"level":"error","spans":[{"file_name":"/checkout/tests/incremental/hashes/enum_constructors.rs","byte_start":2029,"byte_end":2076,"line_start":72,"line_end":72,"column_start":1,"column_end":48,"is_primary":true,"text":[{"text":"pub fn change_field_order_struct_like() -> Enum {","highlight_start":1,"highlight_end":48}],"label":null,"suggested_replacement":null,"suggestion_applicability":null,"expansion":null}],"children":[],"rendered":"error: `optimized_mir(change_field_order_struct_like)` should be dirty but is not\n  --> /checkout/tests/incremental/hashes/enum_constructors.rs:72:1\n   |\nLL | pub fn change_field_order_struct_like() -> Enum {\n   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^\n\n"}
{"$message_type":"diagnostic","message":"aborting due to 1 previous error","code":null,"level":"error","spans":[],"children":[],"rendered":"error: aborting due to 1 previous error\n\n"}

------------------------------------------

error in revision `cfail5`: test compilation failed although it shouldn't!
status: exit status: 1
command: env -u RUSTC_LOG_COLOR RUSTC_ICE="0" RUST_BACKTRACE="short" "/checkout/obj/build/aarch64-unknown-linux-gnu/stage2/bin/rustc" "/checkout/tests/incremental/hashes/enum_constructors.rs" "-Zthreads=1" "-Zsimulate-remapped-rust-src-base=/rustc/FAKE_PREFIX" "-Ztranslate-remapped-path-to-local-path=no" "-Z" "ignore-directory-in-diagnostics-source-blocks=/cargo" "-Z" "ignore-directory-in-diagnostics-source-blocks=/checkout/vendor" "--sysroot" "/checkout/obj/build/aarch64-unknown-linux-gnu/stage2" "--target=aarch64-unknown-linux-gnu" "--cfg" "cfail5" "--check-cfg" "cfg(test,FALSE,cfail1,cfail2,cfail3,cfail4,cfail5,cfail6)" "-C" "incremental=/checkout/obj/build/aarch64-unknown-linux-gnu/test/incremental/hashes/enum_constructors/enum_constructors.inc" "-Z" "incremental-verify-ich" "-O" "--error-format" "json" "--json" "future-incompat" "-Zui-testing" "-Zdeduplicate-diagnostics=no" "-C" "prefer-dynamic" "--out-dir" "/checkout/obj/build/aarch64-unknown-linux-gnu/test/incremental/hashes/enum_constructors" "-A" "internal_features" "-A" "unused_parens" "-A" "unused_braces" "-Crpath" "-Cdebuginfo=0" "-Lnative=/checkout/obj/build/aarch64-unknown-linux-gnu/native/rust-test-helpers" "-Z" "query-dep-graph" "-O"
stdout: none
--- stderr -------------------------------
error: `optimized_mir(change_field_order_struct_like)` should be dirty but is not
##[error]  --> /checkout/tests/incremental/hashes/enum_constructors.rs:72:1
   |
LL | pub fn change_field_order_struct_like() -> Enum {
   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

error: aborting due to 1 previous error
------------------------------------------

---- [incremental] tests/incremental/hashes/enum_constructors.rs stdout end ----
---- [incremental] tests/incremental/hashes/struct_constructors.rs stdout ----
------rustc stdout------------------------------

------rustc stderr------------------------------
{"$message_type":"diagnostic","message":"`optimized_mir(change_field_order_regular_struct)` should be dirty but is not","code":null,"level":"error","spans":[{"file_name":"/checkout/tests/incremental/hashes/struct_constructors.rs","byte_start":1811,"byte_end":1870,"line_start":67,"line_end":67,"column_start":1,"column_end":60,"is_primary":true,"text":[{"text":"pub fn change_field_order_regular_struct() -> RegularStruct {","highlight_start":1,"highlight_end":60}],"label":null,"suggested_replacement":null,"suggestion_applicability":null,"expansion":null}],"children":[],"rendered":"error: `optimized_mir(change_field_order_regular_struct)` should be dirty but is not\n  --> /checkout/tests/incremental/hashes/struct_constructors.rs:67:1\n   |\nLL | pub fn change_field_order_regular_struct() -> RegularStruct {\n   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^\n\n"}
{"$message_type":"diagnostic","message":"aborting due to 1 previous error","code":null,"level":"error","spans":[],"children":[],"rendered":"error: aborting due to 1 previous error\n\n"}

------------------------------------------

error in revision `cfail5`: test compilation failed although it shouldn't!
status: exit status: 1
command: env -u RUSTC_LOG_COLOR RUSTC_ICE="0" RUST_BACKTRACE="short" "/checkout/obj/build/aarch64-unknown-linux-gnu/stage2/bin/rustc" "/checkout/tests/incremental/hashes/struct_constructors.rs" "-Zthreads=1" "-Zsimulate-remapped-rust-src-base=/rustc/FAKE_PREFIX" "-Ztranslate-remapped-path-to-local-path=no" "-Z" "ignore-directory-in-diagnostics-source-blocks=/cargo" "-Z" "ignore-directory-in-diagnostics-source-blocks=/checkout/vendor" "--sysroot" "/checkout/obj/build/aarch64-unknown-linux-gnu/stage2" "--target=aarch64-unknown-linux-gnu" "--cfg" "cfail5" "--check-cfg" "cfg(test,FALSE,cfail1,cfail2,cfail3,cfail4,cfail5,cfail6)" "-C" "incremental=/checkout/obj/build/aarch64-unknown-linux-gnu/test/incremental/hashes/struct_constructors/struct_constructors.inc" "-Z" "incremental-verify-ich" "-O" "--error-format" "json" "--json" "future-incompat" "-Zui-testing" "-Zdeduplicate-diagnostics=no" "-C" "prefer-dynamic" "--out-dir" "/checkout/obj/build/aarch64-unknown-linux-gnu/test/incremental/hashes/struct_constructors" "-A" "internal_features" "-A" "unused_parens" "-A" "unused_braces" "-Crpath" "-Cdebuginfo=0" "-Lnative=/checkout/obj/build/aarch64-unknown-linux-gnu/native/rust-test-helpers" "-Z" "query-dep-graph" "-O"
stdout: none
--- stderr -------------------------------
error: `optimized_mir(change_field_order_regular_struct)` should be dirty but is not
##[error]  --> /checkout/tests/incremental/hashes/struct_constructors.rs:67:1
   |
LL | pub fn change_field_order_regular_struct() -> RegularStruct {
   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

[rust-bors]

☀️ Try build successful (CI)
Build commit: 576a61d (576a61d19539ab75e0e4d0799b5c43a37f899cca, parent: 1be6b13be73dc12e98e51b403add4c41a0b77759)

[rust-timer]

Finished benchmarking commit (576a61d): comparison URL.

Overall result: ❌✅ regressions and improvements - please read the text below

Benchmarking this pull request means it may be perf-sensitive – we'll automatically label it not fit for rolling up. You can override this, but we strongly advise not to, due to possible changes in compiler perf.

Next Steps: If you can justify the regressions found in this try perf run, please do so in sufficient writing along with @rustbot label: +perf-regression-triaged. If not, please fix the regressions and do another perf run. If its results are neutral or positive, the label will be automatically removed.

@bors rollup=never
@rustbot label: -S-waiting-on-perf +perf-regression

Instruction count

Our most reliable metric. Used to determine the overall result above. However, even this metric can be noisy.

	mean	range	count
Regressions ❌ (primary)	0.6%	[0.3%, 1.0%]	3
Regressions ❌ (secondary)	0.2%	[0.1%, 0.2%]	3
Improvements ✅ (primary)	-0.3%	[-0.5%, -0.2%]	15
Improvements ✅ (secondary)	-0.2%	[-0.3%, -0.1%]	2
All ❌✅ (primary)	-0.1%	[-0.5%, 1.0%]	18

Max RSS (memory usage)

Results (primary 0.4%)

A less reliable metric. May be of interest, but not used to determine the overall result above.

	mean	range	count
Regressions ❌ (primary)	4.4%	[3.8%, 5.0%]	2
Regressions ❌ (secondary)	-	-	0
Improvements ✅ (primary)	-2.3%	[-3.7%, -0.9%]	3
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	0.4%	[-3.7%, 5.0%]	5

Cycles

Results (secondary 2.9%)

A less reliable metric. May be of interest, but not used to determine the overall result above.

	mean	range	count
Regressions ❌ (primary)	-	-	0
Regressions ❌ (secondary)	2.9%	[2.9%, 2.9%]	1
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	-	-	0

Binary size

Results (primary -0.0%, secondary 0.0%)

A less reliable metric. May be of interest, but not used to determine the overall result above.

	mean	range	count
Regressions ❌ (primary)	0.2%	[0.0%, 0.5%]	11
Regressions ❌ (secondary)	0.1%	[0.0%, 0.1%]	51
Improvements ✅ (primary)	-0.2%	[-0.5%, -0.1%]	18
Improvements ✅ (secondary)	-0.3%	[-0.6%, -0.1%]	11
All ❌✅ (primary)	-0.0%	[-0.5%, 0.5%]	29

Bootstrap: 468.01s -> 469.007s (0.21%)
Artifact size: 386.86 MiB -> 386.97 MiB (0.03%)