Render pattern types nicely in mir dumps #136176

oli-obk · 2025-01-28T08:22:05Z

avoid falling through to the fallback rendering that just does a hex dump

best reviewed commit by commit

oli-obk · 2025-01-28T08:23:57Z

tests/mir-opt/pattern_types.main.PreCodegen.after.mir

+    scope 1 {
+        debug x => const 2_u32 is 1..=;
+        scope 2 {
+            debug y => const 0_u32 is 1..=;


This one is fun. We do render as transmute for other things that are invalid (e.g. chars that aren't valid chars, or bools that aren't 0 or 1), but it's harder to do this here without running validation on it... and I'm not sure all the extra logic for doing so would be worth it.

compiler-errors

Would be nice if we had some way of statically validating that a ScalarInt is valid in a Layout for this exact check (and it may be useful elsewhere in the compiler).

But looks fine for now.

compiler-errors · 2025-01-28T15:35:11Z

r? compiler-errors @bors r+ rollup

bors · 2025-01-28T15:35:14Z

📌 Commit fd6713f has been approved by compiler-errors

It is now in the queue for this repository.

scottmcm · 2025-01-28T18:20:54Z

tests/mir-opt/pattern_types.rs

+fn main() {
+    // CHECK: debug x => const {transmute(0x00000002): (u32) is 1..=}
+    let x: pattern_type!(u32 is 1..) = unsafe { std::mem::transmute(2) };
+    // CHECK: debug y => const {transmute(0x00000000): (u32) is 1..=}


Hmm, definitely interesting. I guess this is falling under the "compilation doesn't have to detect UB" rule?

Well... we kinda do because there could be no UB, just const prop crossing a check that prevents UB. So this could happen in dead code. So there is an argument for showing that in pretty printing. I'll see if I can pull out the logic we use in const validation in a way that makes it reusable here

…ompiler-errors Render pattern types nicely in mir dumps avoid falling through to the fallback rendering that just does a hex dump r? `@scottmcm` best reviewed commit by commit

Rollup of 9 pull requests Successful merges: - rust-lang#136121 (Deduplicate operand creation between scalars, non-scalars and string patterns) - rust-lang#136134 (Fix SIMD codegen tests on LLVM 20) - rust-lang#136153 (Locate asan-odr-win with other sanitizer tests) - rust-lang#136161 (rustdoc: add nobuild typescript checking to our JS) - rust-lang#136166 (interpret: is_alloc_live: check global allocs last) - rust-lang#136168 (GCI: Don't try to eval / collect mono items inside overly generic free const items) - rust-lang#136170 (Reject unsound toggling of Arm atomics-32 target feature) - rust-lang#136176 (Render pattern types nicely in mir dumps) - rust-lang#136186 (uefi: process: Fix args) r? `@ghost` `@rustbot` modify labels: rollup

Rollup merge of rust-lang#136176 - oli-obk:pattern-type-mir-opts, r=compiler-errors Render pattern types nicely in mir dumps avoid falling through to the fallback rendering that just does a hex dump r? ``@scottmcm`` best reviewed commit by commit

Pretty print pattern type values with transmute if they don't satisfy their pattern Instead of printing `0_u32 is 1..`, we now print the default fallback rendering that we also use for invalid bools, chars, ...: `{transmute(0x00000000): (u32) is 1..=}`. These cases can occur in mir dumps when const prop propagates a constant across a safety check that would prevent the actually UB value from existing. That's fine though, as it's dead code and we always need to allow UB in dead code. follow-up to rust-lang#136176 cc `@compiler-errors` `@scottmcm` r? `@RalfJung` because of the interpreter changes

Pretty print pattern type values with transmute if they don't satisfy their pattern Instead of printing `0_u32 is 1..`, we now print the default fallback rendering that we also use for invalid bools, chars, ...: `{transmute(0x00000000): (u32) is 1..=}`. These cases can occur in mir dumps when const prop propagates a constant across a safety check that would prevent the actually UB value from existing. That's fine though, as it's dead code and we always need to allow UB in dead code. follow-up to rust-lang#136176 cc ``@compiler-errors`` ``@scottmcm`` r? ``@RalfJung`` because of the interpreter changes

Pretty print pattern type values with transmute if they don't satisfy their pattern Instead of printing `0_u32 is 1..`, we now print the default fallback rendering that we also use for invalid bools, chars, ...: `{transmute(0x00000000): (u32) is 1..=}`. These cases can occur in mir dumps when const prop propagates a constant across a safety check that would prevent the actually UB value from existing. That's fine though, as it's dead code and we always need to allow UB in dead code. follow-up to rust-lang#136176 cc ```@compiler-errors``` ```@scottmcm``` r? ```@RalfJung``` because of the interpreter changes

Pretty print pattern type values with transmute if they don't satisfy their pattern Instead of printing `0_u32 is 1..`, we now print the default fallback rendering that we also use for invalid bools, chars, ...: `{transmute(0x00000000): (u32) is 1..=}`. These cases can occur in mir dumps when const prop propagates a constant across a safety check that would prevent the actually UB value from existing. That's fine though, as it's dead code and we always need to allow UB in dead code. follow-up to rust-lang#136176 cc `@compiler-errors` `@scottmcm` r? `@RalfJung` because of the interpreter changes

Pretty print pattern type values with transmute if they don't satisfy their pattern Instead of printing `0_u32 is 1..`, we now print the default fallback rendering that we also use for invalid bools, chars, ...: `{transmute(0x00000000): (u32) is 1..=}`. These cases can occur in mir dumps when const prop propagates a constant across a safety check that would prevent the actually UB value from existing. That's fine though, as it's dead code and we always need to allow UB in dead code. follow-up to rust-lang#136176 cc ``@compiler-errors`` ``@scottmcm`` r? ``@RalfJung`` because of the interpreter changes

Rollup merge of rust-lang#136235 - oli-obk:transmuty-pat-tys, r=RalfJung Pretty print pattern type values with transmute if they don't satisfy their pattern Instead of printing `0_u32 is 1..`, we now print the default fallback rendering that we also use for invalid bools, chars, ...: `{transmute(0x00000000): (u32) is 1..=}`. These cases can occur in mir dumps when const prop propagates a constant across a safety check that would prevent the actually UB value from existing. That's fine though, as it's dead code and we always need to allow UB in dead code. follow-up to rust-lang#136176 cc ``@compiler-errors`` ``@scottmcm`` r? ``@RalfJung`` because of the interpreter changes

Pretty print pattern type values with transmute if they don't satisfy their pattern Instead of printing `0_u32 is 1..`, we now print the default fallback rendering that we also use for invalid bools, chars, ...: `{transmute(0x00000000): (u32) is 1..=}`. These cases can occur in mir dumps when const prop propagates a constant across a safety check that would prevent the actually UB value from existing. That's fine though, as it's dead code and we always need to allow UB in dead code. follow-up to rust-lang/rust#136176 cc ``@compiler-errors`` ``@scottmcm`` r? ``@RalfJung`` because of the interpreter changes

Rollup of 9 pull requests Successful merges: - rust-lang#136121 (Deduplicate operand creation between scalars, non-scalars and string patterns) - rust-lang#136134 (Fix SIMD codegen tests on LLVM 20) - rust-lang#136153 (Locate asan-odr-win with other sanitizer tests) - rust-lang#136161 (rustdoc: add nobuild typescript checking to our JS) - rust-lang#136166 (interpret: is_alloc_live: check global allocs last) - rust-lang#136168 (GCI: Don't try to eval / collect mono items inside overly generic free const items) - rust-lang#136170 (Reject unsound toggling of Arm atomics-32 target feature) - rust-lang#136176 (Render pattern types nicely in mir dumps) - rust-lang#136186 (uefi: process: Fix args) r? `@ghost` `@rustbot` modify labels: rollup

oli-obk added 2 commits January 28, 2025 08:12

Add mir-opt pattern type tests

7877d86

Make mir dumps more readable

fd6713f

rustbot assigned scottmcm Jan 28, 2025

rustbot added S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. T-compiler Relevant to the compiler team, which will review and decide on the PR/issue. labels Jan 28, 2025

oli-obk commented Jan 28, 2025

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compiler-errors approved these changes Jan 28, 2025

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rustbot assigned compiler-errors and unassigned scottmcm Jan 28, 2025

bors added S-waiting-on-bors Status: Waiting on bors to run and complete tests. Bors will change the label on completion. and removed S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. labels Jan 28, 2025

scottmcm reviewed Jan 28, 2025

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Zalathar mentioned this pull request Jan 29, 2025

Rollup of 8 pull requests #136222

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fmease mentioned this pull request Jan 29, 2025

Rollup of 9 pull requests #136227

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oli-obk mentioned this pull request Jan 29, 2025

Pretty print pattern type values with transmute if they don't satisfy their pattern #136235

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bors merged commit f49ad60 into rust-lang:master Jan 29, 2025
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Render pattern types nicely in mir dumps #136176

Render pattern types nicely in mir dumps #136176

oli-obk commented Jan 28, 2025

oli-obk Jan 28, 2025 •

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Render pattern types nicely in mir dumps #136176

Render pattern types nicely in mir dumps #136176

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