[not for review] Investigate ARM test failure in P0811R3_midpoint_lerp

azure-devops/cmake-configure-build.yml

@@ -25,6 +25,7 @@ parameters:
     - '--order=lexical'
     - '--num-shards=$(System.TotalJobsInPhase)'
     - '--run-shard=$(System.JobPositionInPhase)'
+    - '--filter=P0811R3_midpoint_lerp'
 
 steps:
 - task: PowerShell@2

azure-pipelines.yml

@@ -10,160 +10,8 @@ pr:
   drafts: false
 
 stages:
-##### Phase 1: Initial Builds #####
-  - stage: Code_Format
-    dependsOn: []
-    displayName: 'Code Format'
-    pool:
-      name: ${{ variables.x64MediumPoolName }}
-      demands: ${{ variables.poolDemands }}
-    variables:
-    - name: workRoot
-      value: '$(x64MediumPoolWorkRoot)'
-      readonly: true
-    jobs:
-      - template: azure-devops/format-validation.yml
-
-  - stage: Build_x64
-    dependsOn: []
-    displayName: 'Build x64'
-    pool:
-      name: ${{ variables.x64MediumPoolName }}
-      demands: ${{ variables.poolDemands }}
-    variables:
-    - name: workRoot
-      value: '$(x64MediumPoolWorkRoot)'
-      readonly: true
-    jobs:
-      - template: azure-devops/build-and-test.yml
-        parameters:
-          hostArch: x64
-          targetArch: x64
-          targetPlatform: x64
-          analyzeBuild: true
-          buildBenchmarks: true
-          numShards: 1
-          configureTesting: false
-          runTesting: false
-
-  - stage: Build_x86
-    dependsOn: []
-    displayName: 'Build x86'
-    pool:
-      name: ${{ variables.x64MediumPoolName }}
-      demands: ${{ variables.poolDemands }}
-    variables:
-    - name: workRoot
-      value: '$(x64MediumPoolWorkRoot)'
-      readonly: true
-    jobs:
-      - template: azure-devops/build-and-test.yml
-        parameters:
-          hostArch: x86
-          targetArch: x86
-          targetPlatform: x86
-          analyzeBuild: true
-          buildBenchmarks: true
-          numShards: 1
-          configureTesting: false
-          runTesting: false
-
-  - stage: Build_ARM64
-    dependsOn: []
-    displayName: 'Build ARM64'
-    pool:
-      name: ${{ variables.arm64PoolName }}
-      demands: ${{ variables.poolDemands }}
-    variables:
-    - name: workRoot
-      value: '$(arm64PoolWorkRoot)'
-      readonly: true
-    jobs:
-      - template: azure-devops/build-and-test.yml
-        parameters:
-          hostArch: arm64
-          targetArch: arm64
-          targetPlatform: arm64
-          analyzeBuild: true
-          buildBenchmarks: true
-          numShards: 1
-          configureTesting: false
-          runTesting: false
-
-  - stage: Build_ARM64EC
-    dependsOn: []
-    displayName: 'Build ARM64EC'
-    pool:
-      name: ${{ variables.arm64PoolName }}
-      demands: ${{ variables.poolDemands }}
-    variables:
-    - name: workRoot
-      value: '$(arm64PoolWorkRoot)'
-      readonly: true
-    jobs:
-      - template: azure-devops/build-and-test.yml
-        parameters:
-          hostArch: arm64
-          targetArch: arm64
-          targetPlatform: arm64ec
-          analyzeBuild: true
-          buildBenchmarks: true
-          numShards: 1
-          configureTesting: false
-          runTesting: false
-
-  - stage: Configure_Tests
-    dependsOn: []
-    displayName: 'Configure Tests'
-    pool:
-      name: ${{ variables.x64MediumPoolName }}
-      demands: ${{ variables.poolDemands }}
-    variables:
-    - name: workRoot
-      value: '$(x64MediumPoolWorkRoot)'
-      readonly: true
-    jobs:
-      - template: azure-devops/build-and-test.yml
-        parameters:
-          hostArch: x64
-          targetArch: x64
-          targetPlatform: x64
-          numShards: 1
-          buildStl: false
-          runTesting: false
-
-##### Phase 2: Primary Test Architectures #####
-  - stage: Test_x64
-    dependsOn:
-      - Code_Format
-      - Build_x64
-      - Build_x86
-      - Build_ARM64
-      - Build_ARM64EC
-      - Configure_Tests
-    displayName: 'Test x64'
-    pool:
-      name: ${{ variables.x64FastPoolName }}
-      demands: ${{ variables.poolDemands }}
-    variables:
-    - name: workRoot
-      value: '$(x64FastPoolWorkRoot)'
-      readonly: true
-    jobs:
-      - template: azure-devops/build-and-test.yml
-        parameters:
-          hostArch: x64
-          targetArch: x64
-          targetPlatform: x64
-
   - stage: Test_ARM64
-    dependsOn:
-      - Code_Format
-      - Build_x64
-      - Build_x86
-      - Build_ARM64
-      - Build_ARM64EC
-      - Configure_Tests
+    dependsOn: []
     displayName: 'Test ARM64'
     pool:
       name: ${{ variables.arm64PoolName }}
@@ -178,42 +26,4 @@ stages:
           hostArch: arm64
           targetArch: arm64
           targetPlatform: arm64
-
-##### Phase 3: Secondary Test Architectures #####
-  - stage: Test_x86
-    dependsOn:
-      - Test_x64
-      - Test_ARM64
-    displayName: 'Test x86'
-    pool:
-      name: ${{ variables.x64SlowPoolName }}
-      demands: ${{ variables.poolDemands }}
-    variables:
-    - name: workRoot
-      value: '$(x64SlowPoolWorkRoot)'
-      readonly: true
-    jobs:
-      - template: azure-devops/build-and-test.yml
-        parameters:
-          hostArch: x86
-          targetArch: x86
-          targetPlatform: x86
-
-  - stage: Test_ARM64EC
-    dependsOn:
-      - Test_x64
-      - Test_ARM64
-    displayName: 'Test ARM64EC'
-    pool:
-      name: ${{ variables.arm64PoolName }}
-      demands: ${{ variables.poolDemands }}
-    variables:
-    - name: workRoot
-      value: '$(arm64PoolWorkRoot)'
-      readonly: true
-    jobs:
-      - template: azure-devops/build-and-test.yml
-        parameters:
-          hostArch: arm64
-          targetArch: arm64
-          targetPlatform: arm64ec
+          numShards: 2

tests/std/tests/P0811R3_midpoint_lerp/test.cpp

@@ -14,6 +14,7 @@
 #include <limits>
 #include <numeric>
 #include <optional>
+#include <random>
 #include <type_traits>
 
 using namespace std;
@@ -91,11 +92,7 @@ constexpr int fe_major_except = FE_INVALID | FE_DIVBYZERO | FE_OVERFLOW;
 
 bool check_feexcept(
     [[maybe_unused]] const int expected_excepts, [[maybe_unused]] const int except_mask = fe_major_except) {
-#if defined(_M_ARM64) || defined(_M_ARM64EC) // TRANSITION, GH-5685
-    return true;
-#else // ^^^ workaround / no workaround vvv
     return fetestexcept(except_mask) == (expected_excepts & except_mask);
-#endif // ^^^ no workaround ^^^
 }
 #else // ^^^ defined(_M_FP_STRICT) / !defined(_M_FP_STRICT) vvv
 class ExceptGuard {
@@ -1133,6 +1130,38 @@ constexpr bool test_gh_2112() {
     return true;
 }
 
+#ifdef _M_FP_STRICT
+template <typename Ty>
+void test_lerp_exception() {
+    mt19937_64 rng(20260802'064821);
+    uniform_int_distribution<long long> dist_ab(-1LL << 58, (1LL << 58) - 1);
+    uniform_int_distribution<long long> dist_t(-3LL << 52, (5LL << 52) - 1);
+
+    for (int i = 0; i < 1'000'000; ++i) {
+        const long long ia = dist_ab(rng);
+        const long long ib = dist_ab(rng);
+        const long long it = dist_t(rng);
+        const Ty a         = static_cast<Ty>(_Bit_cast<double>(ia ^ (ia >> 63)) * 0x1p+991);
+        const Ty b         = static_cast<Ty>(_Bit_cast<double>(ib ^ (ib >> 63)) * 0x1p+991);
+        const Ty t         = static_cast<Ty>(it * 0x1p-53);
+
+        feclearexcept(FE_ALL_EXCEPT);
+        const Ty result      = lerp(a, b, t);
+        const int exceptions = fetestexcept(FE_ALL_EXCEPT);
+
+        if ((exceptions & ~FE_INEXACT) != 0) {
+            constexpr int hex_precision = (numeric_limits<Ty>::digits - 1 + 3) / 4;
+            printf("         a: %+.*a\n", hex_precision, a);
+            printf("         b: %+.*a\n", hex_precision, b);
+            printf("         t: %+.*a\n", hex_precision, t);
+            printf("    result: %+.*a\n", hex_precision, result);
+            printf("exceptions: %#x\n", exceptions);
+            exit(1);
+        }
+    }
+}
+#endif // _M_FP_STRICT
+
 int main() {
     test_constants<float>();
     test_constants<double>();
@@ -1207,4 +1236,9 @@ int main() {
     test_gh_1917();
     test_gh_2112();
     STATIC_ASSERT(test_gh_2112());
+
+#ifdef _M_FP_STRICT
+    test_lerp_exception<float>();
+    test_lerp_exception<double>();
+#endif // _M_FP_STRICT
 }