Stop needing materialized places for most intrinsics

[scottmcm]

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Today even to return a constant from size_of_val it takes an alloca. That's wasteful.

This updates the cg_ssa traits to allow returning an OperandValue instead, which is possible for the vast majority of intrinsics -- this PR moves all but 5 over to doing that in LLVM.

The first commit adds a test to help show the difference here.

cc rust-lang/compiler-team#970 #153250

[scottmcm]

@bors try @rust-timer queue

[rust-bors]

☀️ Try build successful (CI)
Build commit: ce9f4cc (ce9f4cc0887ef1020c405689861eeb71f9095196, parent: 045b17737dab5fcc28e4cbee0cfe2ce4ed363b32)

[rust-timer]

Finished benchmarking commit (ce9f4cc): comparison URL.

Overall result: ✅ improvements - no action needed

Benchmarking means the PR may be perf-sensitive. Consider adding rollup=never if this change is not fit for rolling up.

@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
Regressions ❌ (secondary)	-	-	0
Improvements ✅ (primary)	-0.1%	[-0.1%, -0.1%]	1
Improvements ✅ (secondary)	-0.3%	[-0.3%, -0.2%]	2
All ❌✅ (primary)	-0.1%	[-0.1%, -0.1%]	1

Max RSS (memory usage)

Results (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
Regressions ❌ (secondary)	2.7%	[0.5%, 7.5%]	5
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-3.5%	[-6.3%, -0.6%]	4
All ❌✅ (primary)	-	-	0

Cycles

Results (secondary -1.2%)

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)	0.7%	[0.6%, 0.7%]	2
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-1.9%	[-5.7%, -0.4%]	5
All ❌✅ (primary)	-	-	0

Binary size

Results (primary -0.1%, secondary -0.1%)

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)	-	-	0
Improvements ✅ (primary)	-0.1%	[-0.2%, -0.1%]	18
Improvements ✅ (secondary)	-0.1%	[-0.2%, -0.0%]	25
All ❌✅ (primary)	-0.1%	[-0.2%, -0.1%]	18

Bootstrap: 496.439s -> 493.878s (-0.52%)
Artifact size: 394.45 MiB -> 394.37 MiB (-0.02%)

[scottmcm]

r? codegen

[rustbot]

The GCC codegen subtree was changed

cc @antoyo, @GuillaumeGomez

[rustbot]

This PR was rebased onto a different main commit. Here's a range-diff highlighting what actually changed.

Rebasing is a normal part of keeping PRs up to date, so no action is needed—this note is just to help reviewers.

[dianqk]

LGTM

View changes since this review

[dianqk]

r=me after CI greens.

[scottmcm]

@bors r=dianqk

[rust-bors]

📌 Commit c4f62d6 has been approved by dianqk

It is now in the queue for this repository.

[rust-bors]

💔 Test for 0ce41cf failed: CI. Failed job:

• auto - x86_64-gnu-debug (web logs, enhanced plaintext logs)

[scottmcm]

@bors try jobs=x86_64-gnu-debug

[rust-bors]

☀️ Try build successful (CI)
Build commit: 6d1a0f5 (6d1a0f55bfb34db3817bb0a2c82f7eeca9fbc013, parent: 54333ff079780f803f65dcee30c544050b35f544)

[dianqk]

@bors r+

[rust-bors]

📌 Commit d3d3485 has been approved by dianqk

It is now in the queue for this repository.

[rust-bors]

💔 Test for 6010ec0 failed: CI. Failed job:

• auto - x86_64-gnu-llvm-22-1 (web logs, enhanced plaintext logs)