Modifies the index instruction from gep [0 x %Type] to gep %Type

[DianQK]

Fixes #133979.

This PR modifies the index instruction from gep [0 x %Type] to gep %Type, which is the same with pointer offset calculation.

This will help LLVM calculate various formats of GEP instructions. According to [RFC] Replacing getelementptr with ptradd, we ultimately aim to canonicalize everything to gep i8. Based on the results from #134117 (comment), I think we still need to investigate some missing optimizations, so this PR is just a small step forward.

r? compiler

[DianQK]

@bors try @rust-timer queue

[bors]

⌛ Trying commit 23cc55f with merge 945e153...

[bors]

☀️ Try build successful - checks-actions
Build commit: 945e153 (945e153a8c0026a060bfa8f7f6e6a0274c42fd72)

[rust-timer]

Finished benchmarking commit (945e153): comparison URL.

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

Benchmarking this pull request likely means that it is perf-sensitive, so we're automatically marking it as not fit for rolling up. While you can manually mark this PR as fit for rollup, we strongly recommend not doing so since this PR may lead to changes in compiler perf.

Next Steps: If you can justify the regressions found in this try perf run, please indicate this with @rustbot label: +perf-regression-triaged along with sufficient written justification. If you cannot justify the regressions please fix the regressions and do another perf run. If the next run shows neutral or positive results, the label will be automatically removed.

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

Instruction count

This is the most reliable metric that we have; it was used to determine the overall result at the top of this comment. However, even this metric can sometimes exhibit noise.

	mean	range	count
Regressions ❌ (primary)	0.3%	[0.1%, 1.1%]	63
Regressions ❌ (secondary)	0.4%	[0.2%, 1.1%]	28
Improvements ✅ (primary)	-0.4%	[-0.6%, -0.2%]	3
Improvements ✅ (secondary)	-0.4%	[-0.8%, -0.2%]	28
All ❌✅ (primary)	0.3%	[-0.6%, 1.1%]	66

Max RSS (memory usage)

Results (primary -3.1%, secondary 2.9%)

This is a less reliable metric that may be of interest but was not used to determine the overall result at the top of this comment.

	mean	range	count
Regressions ❌ (primary)	-	-	0
Regressions ❌ (secondary)	5.4%	[4.7%, 7.1%]	4
Improvements ✅ (primary)	-3.1%	[-3.1%, -3.1%]	1
Improvements ✅ (secondary)	-2.3%	[-2.4%, -2.2%]	2
All ❌✅ (primary)	-3.1%	[-3.1%, -3.1%]	1

Cycles

Results (primary 0.7%)

This is a less reliable metric that may be of interest but was not used to determine the overall result at the top of this comment.

	mean	range	count
Regressions ❌ (primary)	0.7%	[0.7%, 0.7%]	1
Regressions ❌ (secondary)	-	-	0
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	0.7%	[0.7%, 0.7%]	1

Binary size

Results (primary -0.1%, secondary 0.3%)

This is a less reliable metric that may be of interest but was not used to determine the overall result at the top of this comment.

	mean	range	count
Regressions ❌ (primary)	0.2%	[0.0%, 1.1%]	20
Regressions ❌ (secondary)	0.3%	[0.1%, 0.5%]	72
Improvements ✅ (primary)	-0.5%	[-1.4%, -0.1%]	13
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	-0.1%	[-1.4%, 1.1%]	33

Bootstrap: 767.346s -> 767.902s (0.07%)
Artifact size: 330.96 MiB -> 331.08 MiB (0.03%)

[DianQK]

@bors try @rust-timer queue

[bors]

⌛ Trying commit f89b192 with merge 98e1ef7...

[bors]

☀️ Try build successful - checks-actions
Build commit: 98e1ef7 (98e1ef761c76173c125591d946ee291acf60a2da)

[rust-timer]

Finished benchmarking commit (98e1ef7): comparison URL.

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

Benchmarking this pull request likely means that it is perf-sensitive, so we're automatically marking it as not fit for rolling up. While you can manually mark this PR as fit for rollup, we strongly recommend not doing so since this PR may lead to changes in compiler perf.

Next Steps: If you can justify the regressions found in this try perf run, please indicate this with @rustbot label: +perf-regression-triaged along with sufficient written justification. If you cannot justify the regressions please fix the regressions and do another perf run. If the next run shows neutral or positive results, the label will be automatically removed.

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

Instruction count

This is the most reliable metric that we have; it was used to determine the overall result at the top of this comment. However, even this metric can sometimes exhibit noise.

	mean	range	count
Regressions ❌ (primary)	0.1%	[0.1%, 0.1%]	1
Regressions ❌ (secondary)	0.7%	[0.2%, 1.2%]	12
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-1.3%	[-1.4%, -1.2%]	4
All ❌✅ (primary)	0.1%	[0.1%, 0.1%]	1

Max RSS (memory usage)

Results (primary 1.0%, secondary -0.2%)

This is a less reliable metric that may be of interest but was not used to determine the overall result at the top of this comment.

	mean	range	count
Regressions ❌ (primary)	2.9%	[2.4%, 3.4%]	2
Regressions ❌ (secondary)	3.2%	[3.2%, 3.2%]	1
Improvements ✅ (primary)	-2.9%	[-2.9%, -2.9%]	1
Improvements ✅ (secondary)	-1.8%	[-1.9%, -1.7%]	2
All ❌✅ (primary)	1.0%	[-2.9%, 3.4%]	3

Cycles

Results (secondary -5.4%)

This is a less reliable metric that may be of interest but was not used to determine the overall result at the top of this comment.

	mean	range	count
Regressions ❌ (primary)	-	-	0
Regressions ❌ (secondary)	-	-	0
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-5.4%	[-6.3%, -4.9%]	4
All ❌✅ (primary)	-	-	0

Binary size

Results (primary 0.0%, secondary 0.0%)

This is a less reliable metric that may be of interest but was not used to determine the overall result at the top of this comment.

	mean	range	count
Regressions ❌ (primary)	0.0%	[0.0%, 0.0%]	7
Regressions ❌ (secondary)	0.0%	[0.0%, 0.0%]	10
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	0.0%	[0.0%, 0.0%]	7

Bootstrap: 767.862s -> 769.757s (0.25%)
Artifact size: 331.04 MiB -> 331.08 MiB (0.01%)

[oli-obk]

@bors r+

[bors]

📌 Commit 3fc506b has been approved by oli-obk

It is now in the queue for this repository.

[RalfJung]

Cc @nikic

[bors]

⌛ Testing commit 3fc506b with merge a611773...

[bors]

☀️ Test successful - checks-actions
Approved by: oli-obk
Pushing a611773 to master...

[rust-timer]

Finished benchmarking commit (a611773): comparison URL.

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

Our benchmarks found a performance regression caused by this PR.
This might be an actual regression, but it can also be just noise.

Next Steps:

• If the regression was expected or you think it can be justified,
  please write a comment with sufficient written justification, and add
  @rustbot label: +perf-regression-triaged to it, to mark the regression as triaged.
• If you think that you know of a way to resolve the regression, try to create
  a new PR with a fix for the regression.
• If you do not understand the regression or you think that it is just noise,
  you can ask the @rust-lang/wg-compiler-performance working group for help (members of this group
  were already notified of this PR).

@rustbot label: +perf-regression
cc @rust-lang/wg-compiler-performance

Instruction count

This is the most reliable metric that we have; it was used to determine the overall result at the top of this comment. However, even this metric can sometimes exhibit noise.

	mean	range	count
Regressions ❌ (primary)	0.1%	[0.1%, 0.2%]	2
Regressions ❌ (secondary)	0.6%	[0.2%, 1.1%]	17
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-1.3%	[-1.4%, -1.2%]	4
All ❌✅ (primary)	0.1%	[0.1%, 0.2%]	2

Max RSS (memory usage)

Results (primary -3.4%, secondary 1.4%)

This is a less reliable metric that may be of interest but was not used to determine the overall result at the top of this comment.

	mean	range	count
Regressions ❌ (primary)	-	-	0
Regressions ❌ (secondary)	2.3%	[2.0%, 2.6%]	3
Improvements ✅ (primary)	-3.4%	[-3.4%, -3.4%]	1
Improvements ✅ (secondary)	-1.4%	[-1.4%, -1.4%]	1
All ❌✅ (primary)	-3.4%	[-3.4%, -3.4%]	1

Cycles

Results (secondary -5.6%)

This is a less reliable metric that may be of interest but was not used to determine the overall result at the top of this comment.

	mean	range	count
Regressions ❌ (primary)	-	-	0
Regressions ❌ (secondary)	-	-	0
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-5.6%	[-6.0%, -5.3%]	4
All ❌✅ (primary)	-	-	0

Binary size

Results (primary 0.0%, secondary 0.0%)

This is a less reliable metric that may be of interest but was not used to determine the overall result at the top of this comment.

	mean	range	count
Regressions ❌ (primary)	0.0%	[0.0%, 0.0%]	7
Regressions ❌ (secondary)	0.0%	[0.0%, 0.0%]	35
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	0.0%	[0.0%, 0.0%]	7

Bootstrap: 770.433s -> 769.875s (-0.07%)
Artifact size: 333.16 MiB -> 333.19 MiB (0.01%)

[Kobzol]

The post-merge perf. is very similar to the previous perf. runs, which were deemed acceptable during review.

@rustbot label: +perf-regression-triaged