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[libc] fix stdbit include test when not all entrypoints are available#80323

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nickdesaulniers merged 3 commits intollvm:mainfrom
nickdesaulniers:stdbit_include_test2
Feb 1, 2024
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[libc] fix stdbit include test when not all entrypoints are available#80323
nickdesaulniers merged 3 commits intollvm:mainfrom
nickdesaulniers:stdbit_include_test2

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@nickdesaulniers nickdesaulniers commented Feb 1, 2024

The intent of the test is to check that:

  1. The type generic macros are defined.
  2. Those macros dispatch to the correct underlying function.

The issue is that when new functionality is added to our stdbit.h without
rolling out the new entrypoint to all targets, this test breaks because our
generated stdbit.h will not contain declarations for the underlying function.
In that case, we should just declare the underlying functions first before
including our generated stdbit.h which just contains declarations. A definition
is a declaration, but redeclarations must match, hence the additions of
noexcept and extern "C".

@nickdesaulniers
[libc] fix stdbit include test when not all entrypoints are available
e55fb44 
The intent of the test is to check that:
1. The type generic macros are defined.
2. Those macros dispatch to the correct underlying function.

The issue is that when new functionality is added to our stdbit.h without
rolling out the new entrypoint to all targets, this test breaks because our
generated stdbit.h will not contain declarations for the underlying function.
In that case, we should just declare the underlying functions first before
including our generated stdbit.h which just contains declarations. A definition
is a declaration, but redeclarations must match, hence the additions of
noexcept and extern "C".
@llvmbot llvmbot added the libc label Feb 1, 2024
@nickdesaulniers nickdesaulniers mentioned this pull request Feb 1, 2024
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llvmbot commented Feb 1, 2024

@llvm/pr-subscribers-libc

Author: Nick Desaulniers (nickdesaulniers)

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The intent of the test is to check that:

  1. The type generic macros are defined.
  2. Those macros dispatch to the correct underlying function.

The issue is that when new functionality is added to our stdbit.h without
rolling out the new entrypoint to all targets, this test breaks because our
generated stdbit.h will not contain declarations for the underlying function.
In that case, we should just declare the underlying functions first before
including our generated stdbit.h which just contains declarations. A definition
is a declaration, but redeclarations must match, hence the additions of
noexcept and extern "C".

Full diff: https://github.com/llvm/llvm-project/pull/80323.diff

1 Files Affected:

  • (modified) libc/test/include/stdbit_test.cpp (+18-12)
diff --git a/libc/test/include/stdbit_test.cpp b/libc/test/include/stdbit_test.cpp
index 61e241c8f68a9..4e8498621b683 100644
--- a/libc/test/include/stdbit_test.cpp
+++ b/libc/test/include/stdbit_test.cpp
@@ -8,8 +8,6 @@
 
 #include "test/UnitTest/Test.h"
 
-#include <stdbit.h>
-
 /*
  * The intent of this test is validate that:
  * 1. We provide the definition of the various type generic macros of stdbit.h.
@@ -18,16 +16,24 @@
  * do not contain non-namespaced symbols.
  */
 
-unsigned char stdc_leading_zeros_uc(unsigned char) { return 0xAA; }
-unsigned short stdc_leading_zeros_us(unsigned short) { return 0xAB; }
-unsigned stdc_leading_zeros_ui(unsigned) { return 0xAC; }
-unsigned long stdc_leading_zeros_ul(unsigned long) { return 0xAD; }
-unsigned long long stdc_leading_zeros_ull(unsigned long long) { return 0xAF; }
-unsigned char stdc_leading_ones_uc(unsigned char) { return 0xBA; }
-unsigned short stdc_leading_ones_us(unsigned short) { return 0xBB; }
-unsigned stdc_leading_ones_ui(unsigned) { return 0xBC; }
-unsigned long stdc_leading_ones_ul(unsigned long) { return 0xBD; }
-unsigned long long stdc_leading_ones_ull(unsigned long long) { return 0xBF; }
+/*
+ * Declare these BEFORE including stdbit.h so that this test may still be run
+ * even if a given target doesn't yet have these individual entrypoints enabled.
+ */
+extern "C" {
+unsigned char stdc_leading_zeros_uc(unsigned char) noexcept { return 0xAA; }
+unsigned short stdc_leading_zeros_us(unsigned short) noexcept { return 0xAB; }
+unsigned stdc_leading_zeros_ui(unsigned) noexcept { return 0xAC; }
+unsigned long stdc_leading_zeros_ul(unsigned long) noexcept { return 0xAD; }
+unsigned long long stdc_leading_zeros_ull(unsigned long long) noexcept { return 0xAF; }
+unsigned char stdc_leading_ones_uc(unsigned char) noexcept { return 0xBA; }
+unsigned short stdc_leading_ones_us(unsigned short) noexcept { return 0xBB; }
+unsigned stdc_leading_ones_ui(unsigned) noexcept { return 0xBC; }
+unsigned long stdc_leading_ones_ul(unsigned long) noexcept { return 0xBD; }
+unsigned long long stdc_leading_ones_ull(unsigned long long) noexcept { return 0xBF; }
+}
+
+#include <stdbit.h>
 
 TEST(LlvmLibcStdbitTest, TypeGenericMacroLeadingZeros) {
   EXPECT_EQ(stdc_leading_zeros(static_cast<unsigned char>(0U)),

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✅ With the latest revision this PR passed the C/C++ code formatter.

@nickdesaulniers nickdesaulniers merged commit f883365 into llvm:main Feb 1, 2024
@nickdesaulniers nickdesaulniers deleted the stdbit_include_test2 branch February 1, 2024 20:08
ichaer added a commit to ichaer/llvm-project-onesided_lower_bound that referenced this pull request Feb 2, 2024
@ichaer
Merge remote-tracking branch 'llvm/main' into onesided_lower_bound
f17fa58 
* llvm/main: (500 commits)
  [docs] Add beginner-focused office hours (llvm#80308)
  [mlir][sparse] external entry method wrapper for sparse tensors (llvm#80326)
  [StackSlotColoring] Ignore non-spill objects in RemoveDeadStores. (llvm#80242)
  [libc][stdbit] fix return types (llvm#80337)
  Revert "[RISCV] Refine cost on Min/Max reduction" (llvm#80340)
  [TTI]Add support for strided loads/stores.
  [analyzer][HTMLRewriter] Cache partial rewrite results. (llvm#80220)
  [flang][openacc][openmp] Use #0 from hlfir.declare value when generating bound ops (llvm#80317)
  [AArch64][PAC] Expand blend(reg, imm) operation in aarch64-pauth pass (llvm#74729)
  [SHT_LLVM_BB_ADDR_MAP][llvm-readobj] Implements llvm-readobj handling for PGOAnalysisMap. (llvm#79520)
  [libc] add bazel support for most of unistd (llvm#80078)
  [clang-tidy] Remove enforcement of rule C.48 from cppcoreguidelines-prefer-member-init (llvm#80330)
  [OpenMP] Fix typo (NFC) (llvm#80332)
  [BOLT] Enable re-writing of Linux kernel binary (llvm#80228)
  [BOLT] Adjust section sizes based on file offsets (llvm#80226)
  [libc] fix stdbit include test when not all entrypoints are available (llvm#80323)
  [RISCV][GISel] RegBank select and instruction select for vector G_ADD, G_SUB (llvm#74114)
  [RISCV] Add srmcfg CSR from Ssqosid extension. (llvm#79914)
  [mlir][sparse] add sparsification options to pretty print and debug s… (llvm#80205)
  [RISCV][MC] MC layer support for the experimental zalasr extension (llvm#79911)
  ...
agozillon pushed a commit to agozillon/llvm-project that referenced this pull request Feb 5, 2024
@nickdesaulniers @agozillon
[libc] fix stdbit include test when not all entrypoints are available (…
c733748 
…llvm#80323)

The intent of the test is to check that: 1. The type generic macros are
defined. 2. Those macros dispatch to the correct underlying function.

The issue is that when new functionality is added to our stdbit.h without
rolling out the new entrypoint to all targets, this test breaks because our
generated stdbit.h will not contain declarations for the underlying function.
In that case, we should just declare the underlying functions first before
including our generated stdbit.h which just contains declarations. A definition
is a declaration, but redeclarations must match, hence the additions of
noexcept and extern "C".
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@lntue lntue lntue approved these changes

@michaelrj-google michaelrj-google Awaiting requested review from michaelrj-google

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