Auto merge of #159628 - Mark-Simulacrum:ci-experiments, r=<try>

CI experiments

Author: bors

rust-bors.toml

@@ -87,31 +87,20 @@ images = {
     "arm64ami" = "latest-gha-runner-ami-arm64",
 }
 jit_runner = "organization"
+# Prices per hour of on-demand compute in us-east-2 (as of Aug 2026)
+# See build speed estimates in https://github.com/rust-lang/simpleinfra/issues/1132
 allowed_instances = [
-    # AMD Zen 5 (x86_64) instances, a subset of these is used in production.
-    # Prices per hour of on-demand compute in us-east-2 (as of Aug 2026)
-    # See rough assessment of build speed for dist-x86_64-quick in https://github.com/rust-lang/simpleinfra/issues/1132
-    # m8a.2x     8 vCPU, 32 GB   $0.48688/hr
-    # c8a.4x    16 vCPU, 32 GB   $0.86216/hr
-    # c8a.8x    32 vCPU, 64 GB   $1.72432/hr
-    # c8a.12x   48 vCPU, 96 GB   $2.58648/hr
-    # CodeBuild 36 vCPU          $4.78799/hr
-    "m8a.2xlarge",
-    "c8a.4xlarge",
-    "c8a.8xlarge",
-    "c8a.12xlarge",
+    # AMD Zen 5 (x86_64)
+    "m8a.2xlarge",  # $0.48688/hr
+    "c8a.4xlarge",  # $0.86216/hr
+    "c8a.8xlarge",  # $1.72432/hr
+    "c8a.12xlarge", # $2.58648/hr
 
-    # Graviton 4 (aarch64) instances, currently just for experimentation
-    "m8g.2xlarge",
-    "c8g.4xlarge",
-    "c8g.8xlarge",
-    "c8g.12xlarge",
-
-    # Graviton 5 (aarch64) instances, currently just for experimentation
-    "m9g.2xlarge",
-    "c9g.4xlarge",
-    "c9g.8xlarge",
-    "c9g.12xlarge",
+    # Graviton (aarch64)
+    "m9g.2xlarge",  # $0.39136/hr
+    "c9g.4xlarge",  # $0.69312/hr
+    "c9g.8xlarge",  # $1.38624/hr
+    "c9g.12xlarge", # $2.07936/hr
 ]
 
 # Enable unrolling of rollup member PRs after rollup merge

src/ci/github-actions/jobs.yml

@@ -61,6 +61,19 @@ runners:
     os: ec2-x86_64ami-m8a.2xlarge-x64-linux-$github.run_id-$github.run_attempt
     <<: *base-job
 
+  - &job-linux-aarch64-8c-ec2
+    os: ec2-arm64ami-m9g.2xlarge-aarch64-linux-$github.run_id-$github.run_attempt
+    <<: *base-job
+
+  - &job-linux-aarch64-16c-ec2
+    os: ec2-arm64ami-c9g.4xlarge-aarch64-linux-$github.run_id-$github.run_attempt
+    <<: *base-job
+
+  - &job-linux-aarch64-32c-ec2
+    os: ec2-arm64ami-c9g.8xlarge-aarch64-linux-$github.run_id-$github.run_attempt
+    <<: *base-job
+
+
 envs:
   production:
     &production
@@ -187,10 +200,12 @@ optional:
       CODEGEN_BACKENDS: llvm,cranelift
       DOCKER_SCRIPT: dist.sh
       DIST_TRY_BUILD: 1
-  # We repeat the try job here so that it can be explicitly executed using `@bors try jobs`, to test
-  # full x64 Linux dist try builds on EC2.
-  - <<: [*job-dist-x86_64-linux, *job-linux-x86-32c-ec2]
-    name: dist-x86_64-linux-quick
+  - name: dist-aarch64-linux-quick
+    env:
+      IMAGE: dist-aarch64-linux
+      CODEGEN_BACKENDS: llvm,cranelift
+      DIST_TRY_BUILD: 1
+    <<: *job-linux-aarch64-32c-ec2
 
 # Main CI jobs that have to be green to merge a commit into the default branch.
 #
@@ -218,10 +233,23 @@ auto:
   - name: armhf-gnu
     <<: *job-linux-4c
 
-  - name: dist-aarch64-linux
+  - name: dist-aarch64-linux-8c
+    env:
+      IMAGE: dist-aarch64-linux
+      CODEGEN_BACKENDS: llvm,cranelift
+    <<: *job-linux-aarch64-8c-ec2
+
+  - name: dist-aarch64-linux-16c
+    env:
+      IMAGE: dist-aarch64-linux
+      CODEGEN_BACKENDS: llvm,cranelift
+    <<: *job-linux-aarch64-16c-ec2
+
+  - name: dist-aarch64-linux-32c
     env:
+      IMAGE: dist-aarch64-linux
       CODEGEN_BACKENDS: llvm,cranelift
-    <<: *job-aarch64-linux-8c
+    <<: *job-linux-aarch64-32c-ec2
 
   - name: dist-android
     <<: *job-linux-4c