std.Target: Add FloatAbi.hard32 and isSoft()/isHard() functions.

We need the extra ABI to represent the 3 float ABIs on RISC-V and LoongArch:

* ilp32/lp64 (soft float)
* ilp32f/lp64f (hard float for f32)
* ilp32d/lp64d (hard float for f32 and f64)

Author: alexrp

lib/compiler_rt/common.zig

@@ -83,13 +83,8 @@ pub fn panic(msg: []const u8, error_return_trace: ?*std.builtin.StackTrace, _: ?
 /// here in compiler-rt.
 pub fn F16T(comptime OtherType: type) type {
     return switch (builtin.cpu.arch) {
-        .arm, .armeb, .thumb, .thumbeb => if (std.Target.arm.featureSetHas(builtin.cpu.features, .has_v8))
-            switch (builtin.abi.floatAbi()) {
-                .soft => u16,
-                .hard => f16,
-            }
-        else
-            u16,
+        .arm, .armeb, .thumb, .thumbeb,
+        => if (std.Target.arm.featureSetHas(builtin.cpu.features, .has_v8) and builtin.abi.isHardFloat()) f16 else u16,
         .aarch64, .aarch64_be, .aarch64_32 => f16,
         .riscv64 => if (builtin.zig_backend == .stage1) u16 else f16,
         .x86, .x86_64 => if (builtin.target.isDarwin()) switch (OtherType) {

lib/std/Target.zig

@@ -755,6 +755,14 @@ pub const Abi = enum {
             else => .soft,
         };
     }
+
+    pub inline fn isSoftFloat(abi: Abi) bool {
+        return abi.floatAbi().isSoft();
+    }
+
+    pub inline fn isHardFloat(abi: Abi) bool {
+        return abi.floatAbi().isHard();
+    }
 };
 
 pub const ObjectFormat = enum {
@@ -1645,15 +1653,41 @@ pub inline fn isSpirV(target: Target) bool {
     return target.cpu.arch.isSpirV();
 }
 
+/// Most architectures only make the distinction between soft float and hard float, and assume that
+/// hard float implies that both `f32` and `f64` have hardware support, while soft float implies
+/// that both are emulated. We use `.soft` and `.hard` for these cases.
+///
+/// Some architectures, however, have three floating point ABIs: Soft float, hard float for just
+/// `f32`, and hard float for both `f32` and `f64`. Here, hard float for both is usually the norm,
+/// with hard float for just `f32` being more common in embedded scenarios. This is the case for
+/// RISC-V and LoongArch, for example. We use `.hard32` to refer to the case where only `f32` has
+/// hardware support.
 pub const FloatAbi = enum {
-    hard,
     soft,
+    hard,
+    hard32,
+
+    pub inline fn isSoft(abi: FloatAbi) bool {
+        return abi == .soft;
+    }
+
+    pub inline fn isHard(abi: FloatAbi) bool {
+        return !abi.isSoft();
+    }
 };
 
-pub inline fn getFloatAbi(target: Target) FloatAbi {
+pub inline fn floatAbi(target: Target) FloatAbi {
     return target.abi.floatAbi();
 }
 
+pub inline fn isSoftFloat(target: Target) bool {
+    return target.floatAbi().isSoft();
+}
+
+pub inline fn isHardFloat(target: Target) bool {
+    return target.floatAbi().isHard();
+}
+
 pub inline fn hasDynamicLinker(target: Target) bool {
     if (target.cpu.arch.isWasm()) {
         return false;
@@ -1733,7 +1767,7 @@ pub const DynamicLinker = struct {
                 .thumbeb => .armeb,
                 else => cpu.arch,
             }),
-            if (cpu.arch.isArmOrThumb() and abi.floatAbi() == .hard) "hf" else "",
+            if (cpu.arch.isArmOrThumb() and abi.isHardFloat()) "hf" else "",
         }) catch unreachable else switch (os_tag) {
             .freebsd => init("/libexec/ld-elf.so.1"),
             .netbsd => init("/libexec/ld.elf_so"),
@@ -1754,10 +1788,7 @@ pub const DynamicLinker = struct {
                 .armeb,
                 .thumb,
                 .thumbeb,
-                => initFmt("/lib/ld-linux{s}.so.3", .{switch (abi.floatAbi()) {
-                    .hard => "-armhf",
-                    else => "",
-                }}) catch unreachable,
+                => initFmt("/lib/ld-linux{s}.so.3", .{if (abi.isHardFloat()) "-armhf" else ""}) catch unreachable,
 
                 .mips,
                 .mipsel,

src/libunwind.zig

@@ -131,7 +131,7 @@ pub fn buildStaticLib(comp: *Compilation, prog_node: std.Progress.Node) BuildErr
         if (!comp.config.any_non_single_threaded) {
             try cflags.append("-D_LIBUNWIND_HAS_NO_THREADS");
         }
-        if (target.cpu.arch.isARM() and target.abi.floatAbi() == .hard) {
+        if (target.cpu.arch.isARM() and target.isHardFloat()) {
             try cflags.append("-DCOMPILER_RT_ARMHF_TARGET");
         }
         try cflags.append("-Wno-bitwise-conditional-parentheses");