compiler: only calculate functionInfo once

This is a small change that's not really important in itself, but it
avoids duplicate errors in a future commit that adds error messages to
//go:wasmimport.

compiler/compiler.go

@@ -82,6 +82,7 @@ type compilerContext struct {
 	uintptrType      llvm.Type
 	program          *ssa.Program
 	diagnostics      []error
+	functionInfos    map[*ssa.Function]functionInfo
 	astComments      map[string]*ast.CommentGroup
 	embedGlobals     map[string][]*loader.EmbedFile
 	pkg              *types.Package
@@ -93,13 +94,14 @@ type compilerContext struct {
 // importantly with a newly created LLVM context and module.
 func newCompilerContext(moduleName string, machine llvm.TargetMachine, config *Config, dumpSSA bool) *compilerContext {
 	c := &compilerContext{
-		Config:      config,
-		DumpSSA:     dumpSSA,
-		difiles:     make(map[string]llvm.Metadata),
-		ditypes:     make(map[types.Type]llvm.Metadata),
-		machine:     machine,
-		targetData:  machine.CreateTargetData(),
-		astComments: map[string]*ast.CommentGroup{},
+		Config:        config,
+		DumpSSA:       dumpSSA,
+		difiles:       make(map[string]llvm.Metadata),
+		ditypes:       make(map[types.Type]llvm.Metadata),
+		machine:       machine,
+		targetData:    machine.CreateTargetData(),
+		functionInfos: map[*ssa.Function]functionInfo{},
+		astComments:   map[string]*ast.CommentGroup{},
 	}
 
 	c.ctx = llvm.NewContext()

compiler/symbol.go

@@ -239,12 +239,16 @@ func (c *compilerContext) getFunction(fn *ssa.Function) (llvm.Type, llvm.Value)
 // present in *ssa.Function, such as the link name and whether it should be
 // exported.
 func (c *compilerContext) getFunctionInfo(f *ssa.Function) functionInfo {
+	if info, ok := c.functionInfos[f]; ok {
+		return info
+	}
 	info := functionInfo{
 		// Pick the default linkName.
 		linkName: f.RelString(nil),
 	}
 	// Check for //go: pragmas, which may change the link name (among others).
 	info.parsePragmas(f)
+	c.functionInfos[f] = info
 	return info
 }