riscv: add "target-abi" metadata flag

This flag is necessary in LLVM 15 because it appears that LLVM 15 has
changed the default target ABI from lp64 to lp64d. This results in a
linker failure. Setting the "target-abi" forces the RISC-V backend to
use the intended target ABI.

compiler/compiler.go

@@ -41,6 +41,7 @@ type Config struct {
 	Triple          string
 	CPU             string
 	Features        string
+	ABI             string
 	GOOS            string
 	GOARCH          string
 	CodeModel       string
@@ -321,6 +322,18 @@ func CompilePackage(moduleName string, pkg *loader.Package, ssaPkg *ssa.Package,
 		c.dibuilder.Destroy()
 	}
 
+	// Add the "target-abi" flag, which is necessary on RISC-V otherwise it will
+	// pick one that doesn't match the -mabi Clang flag.
+	if c.ABI != "" {
+		c.mod.AddNamedMetadataOperand("llvm.module.flags",
+			c.ctx.MDNode([]llvm.Metadata{
+				llvm.ConstInt(c.ctx.Int32Type(), 1, false).ConstantAsMetadata(), // Error on mismatch
+				c.ctx.MDString("target-abi"),
+				c.ctx.MDString(c.ABI),
+			}),
+		)
+	}
+
 	return c.mod, c.diagnostics
 }
 

compiler/compiler_test.go

@@ -73,6 +73,7 @@ func TestCompiler(t *testing.T) {
 			compilerConfig := &Config{
 				Triple:             config.Triple(),
 				Features:           config.Features(),
+				ABI:                config.ABI(),
 				GOOS:               config.GOOS(),
 				GOARCH:             config.GOARCH(),
 				CodeModel:          config.CodeModel(),