[bazel] Improve libc build on macOS

[keith]

With these changes you can now bazel build @llvm-project//... on macOS, and the targets in libc that don't yet support macOS (or non-linux) are ignored

[llvmbot]

@llvm/pr-subscribers-libc

Author: Keith Smiley (keith)

Changes

This isn't enough to get everything in libc working, but I started down this path and these were the first required fixes. I might get back to more changes later.

---

Full diff: https://github.com/llvm/llvm-project/pull/86174.diff

1 Files Affected:

• (modified) utils/bazel/llvm-project-overlay/libc/BUILD.bazel (+31-14)

diff --git a/utils/bazel/llvm-project-overlay/libc/BUILD.bazel b/utils/bazel/llvm-project-overlay/libc/BUILD.bazel
index c4f6eab0622181..59855dbef7bb05 100644
--- a/utils/bazel/llvm-project-overlay/libc/BUILD.bazel
+++ b/utils/bazel/llvm-project-overlay/libc/BUILD.bazel
@@ -742,12 +742,12 @@ libc_support_library(
     deps = [
         ":__support_common",
         ":__support_cpp_bit",
-        ":__support_sign",
         ":__support_cpp_type_traits",
         ":__support_libc_assert",
         ":__support_macros_attributes",
         ":__support_macros_properties_types",
         ":__support_math_extras",
+        ":__support_sign",
         ":__support_uint128",
     ],
 )
@@ -964,11 +964,17 @@ libc_support_library(
 libc_support_library(
     name = "__support_osutil_syscall",
     hdrs = ["src/__support/OSUtil/syscall.h"],
-    textual_hdrs = [
-        "src/__support/OSUtil/linux/syscall.h",
-        "src/__support/OSUtil/linux/aarch64/syscall.h",
-        "src/__support/OSUtil/linux/x86_64/syscall.h",
-    ],
+    textual_hdrs = select({
+        "@platforms//os:macos": [
+            "src/__support/OSUtil/darwin/syscall.h",
+            "src/__support/OSUtil/darwin/arm/syscall.h",
+        ],
+        "//conditions:default": [
+            "src/__support/OSUtil/linux/syscall.h",
+            "src/__support/OSUtil/linux/aarch64/syscall.h",
+            "src/__support/OSUtil/linux/x86_64/syscall.h",
+        ],
+    }),
     deps = [
         ":__support_common",
         ":__support_cpp_bit",
@@ -978,9 +984,10 @@ libc_support_library(
 libc_support_library(
     name = "__support_osutil_io",
     hdrs = ["src/__support/OSUtil/io.h"],
-    textual_hdrs = [
-        "src/__support/OSUtil/linux/io.h",
-    ],
+    textual_hdrs = select({
+        "@platforms//os:macos": ["src/__support/OSUtil/darwin/io.h"],
+        "//conditions:default": ["src/__support/OSUtil/linux/io.h"],
+    }),
     deps = [
         ":__support_common",
         ":__support_cpp_string_view",
@@ -992,10 +999,15 @@ libc_support_library(
 libc_support_library(
     name = "__support_osutil_quick_exit",
     hdrs = ["src/__support/OSUtil/quick_exit.h"],
-    textual_hdrs = [
-        "src/__support/OSUtil/linux/quick_exit.h",
-        #TODO: add support for GPU quick_exit (isn't just in a header.)
-    ],
+    textual_hdrs = select({
+        "@platforms//os:macos": [
+            "src/__support/OSUtil/darwin/quick_exit.h",
+        ],
+        "//conditions:default": [
+            "src/__support/OSUtil/linux/quick_exit.h",
+            #TODO: add support for GPU quick_exit (isn't just in a header.)
+        ],
+    }),
     deps = [
         ":__support_osutil_syscall",
     ],
@@ -1927,7 +1939,12 @@ libc_math_function(name = "copysignf")
 
 libc_math_function(name = "copysignl")
 
-libc_math_function(name = "copysignf128")
+libc_math_function(
+    name = "copysignf128",
+    additional_deps = [
+        ":llvm_libc_types_float128",
+    ],
+)
 
 libc_math_function(name = "ilogb")
 

[michaelrj-google]

This patch LGTM, I will warn you that there hasn't been much work on the MacOS build (bazel or cmake) recently so there may be some broken pieces. Feel free to send issues my way, but also we could absolutely use your expertise in bringing it online.

[keith]

good to know thanks! I'm not sure how much more I will try to do, originally I just set out to do a bazel build ... and started dealing with the failures, but I'm not sure if we will have a dep on this that will require more fixes, we'll see!

[keith]

rebased and pushed some more changes so now nothing fails to build on macOS (but many things are just skipped)

[gchatelet]

LGTM modulo a few comments. I'd need to check that this is compatible with downstream before landing this change.

[gchatelet]

Downstream is happy, LGTM