From be35d37d8b6c206576ff3cdcad956d921b47cc6b Mon Sep 17 00:00:00 2001
From: Trevor Gross <tmgross@umich.edu>
Date: Mon, 30 Jun 2025 16:53:21 -0500
Subject: Use the compiler to determine whether or not to enable `f16` and
 `f128`

Currently we whether or not to build and test `f16` and `f128` support
mostly based on the target triple. This isn't always accurate, however,
since support also varies by backend and the backend version.

Since recently, `rustc` is aware of this with the unstable config option
`target_has_reliable_{f16,f128}`, which better represents when the types
are actually expected to be available and usable. Switch our
compiler-builtins and libm configuration to use this by probing `rustc`
for the target's settings.

A few small `cfg` fixes are needed with this.
---
 library/compiler-builtins/builtins-test/benches/float_cmp.rs | 2 ++
 library/compiler-builtins/builtins-test/build.rs             | 1 -
 library/compiler-builtins/builtins-test/tests/conv.rs        | 4 ++--
 library/compiler-builtins/builtins-test/tests/div_rem.rs     | 4 ++--
 4 files changed, 6 insertions(+), 5 deletions(-)

(limited to 'library/compiler-builtins/builtins-test')

diff --git a/library/compiler-builtins/builtins-test/benches/float_cmp.rs b/library/compiler-builtins/builtins-test/benches/float_cmp.rs
index 87a89efb5a4..da29b5d3132 100644
--- a/library/compiler-builtins/builtins-test/benches/float_cmp.rs
+++ b/library/compiler-builtins/builtins-test/benches/float_cmp.rs
@@ -177,6 +177,7 @@ float_bench! {
     ],
 }
 
+#[cfg(f128_enabled)]
 float_bench! {
     name: cmp_f128_gt,
     sig: (a: f128, b: f128) -> CmpResult,
@@ -189,6 +190,7 @@ float_bench! {
     asm: []
 }
 
+#[cfg(f128_enabled)]
 float_bench! {
     name: cmp_f128_unord,
     sig: (a: f128, b: f128) -> CmpResult,
diff --git a/library/compiler-builtins/builtins-test/build.rs b/library/compiler-builtins/builtins-test/build.rs
index e8f4eb4dd22..5b2dcd12ef8 100644
--- a/library/compiler-builtins/builtins-test/build.rs
+++ b/library/compiler-builtins/builtins-test/build.rs
@@ -116,5 +116,4 @@ fn main() {
     }
 
     builtins_configure::configure_aliases(&target);
-    builtins_configure::configure_f16_f128(&target);
 }
diff --git a/library/compiler-builtins/builtins-test/tests/conv.rs b/library/compiler-builtins/builtins-test/tests/conv.rs
index 491915d9bb1..7d729364fae 100644
--- a/library/compiler-builtins/builtins-test/tests/conv.rs
+++ b/library/compiler-builtins/builtins-test/tests/conv.rs
@@ -118,7 +118,7 @@ mod i_to_f {
         i128, __floattidf;
     }
 
-    #[cfg(not(feature = "no-f16-f128"))]
+    #[cfg(f128_enabled)]
     #[cfg(not(any(target_arch = "powerpc", target_arch = "powerpc64")))]
     i_to_f! { f128, Quad, not(feature = "no-sys-f128-int-convert"),
         u32, __floatunsitf;
@@ -129,7 +129,7 @@ mod i_to_f {
         i128, __floattitf;
     }
 
-    #[cfg(not(feature = "no-f16-f128"))]
+    #[cfg(f128_enabled)]
     #[cfg(any(target_arch = "powerpc", target_arch = "powerpc64"))]
     i_to_f! { f128, Quad, not(feature = "no-sys-f128-int-convert"),
         u32, __floatunsikf;
diff --git a/library/compiler-builtins/builtins-test/tests/div_rem.rs b/library/compiler-builtins/builtins-test/tests/div_rem.rs
index 5ae653cc90c..e8327f9b4b8 100644
--- a/library/compiler-builtins/builtins-test/tests/div_rem.rs
+++ b/library/compiler-builtins/builtins-test/tests/div_rem.rs
@@ -147,7 +147,7 @@ mod float_div {
         f64, __divdf3, Double, all();
     }
 
-    #[cfg(not(feature = "no-f16-f128"))]
+    #[cfg(f128_enabled)]
     #[cfg(not(any(target_arch = "powerpc", target_arch = "powerpc64")))]
     float! {
         f128, __divtf3, Quad,
@@ -156,7 +156,7 @@ mod float_div {
         not(any(feature = "no-sys-f128", all(target_arch = "aarch64", target_os = "linux")));
     }
 
-    #[cfg(not(feature = "no-f16-f128"))]
+    #[cfg(f128_enabled)]
     #[cfg(any(target_arch = "powerpc", target_arch = "powerpc64"))]
     float! {
         f128, __divkf3, Quad, not(feature = "no-sys-f128");
-- 
cgit 1.4.1-3-g733a5