diff --git a/src/codegen/llvm.zig b/src/codegen/llvm.zig index 59df12df61..d7d1be6a50 100644 --- a/src/codegen/llvm.zig +++ b/src/codegen/llvm.zig @@ -3108,6 +3108,30 @@ pub const Object = struct { .value = .empty, } }, &o.builder); } + if (target.floatAbi() == .soft) { + // `use-soft-float` means "use software routines for floating point computations". In + // other words, it configures how LLVM lowers basic float instructions like `fcmp`, + // `fadd`, etc. The float calling convention is configured on `TargetMachine` and is + // mostly an orthogonal concept, although obviously we do need hardware float operations + // to actually be able to pass float values in float registers. + // + // Ideally, we would support something akin to the `-mfloat-abi=softfp` option that GCC + // and Clang support for Arm32 and CSKY. We don't currently expose such an option in + // Zig, and using CPU features as the source of truth for this makes for a miserable + // user experience since people expect e.g. `arm-linux-gnueabi` to mean full soft float + // unless the compiler has explicitly been told otherwise. (And note that our baseline + // CPU models almost all include FPU features!) + // + // Revisit this at some point. + try attributes.addFnAttr(.{ .string = .{ + .kind = try o.builder.string("use-soft-float"), + .value = try o.builder.string("true"), + } }, &o.builder); + + // This prevents LLVM from using FPU/SIMD code for things like `memcpy`. As for the + // above, this should be revisited if `softfp` support is added. + try attributes.addFnAttr(.noimplicitfloat, &o.builder); + } } fn resolveGlobalUav(