I suspect it's because Go 1.8 cmd/asm compiles multiple assembly files together.

A minimal test case: $ mkdir t $ cd t $ cat > a.s <<EOF DATA ·constants<>+0x0(SB)/8,$0 GLOBL ·constants<>(SB),8,$8 EOF $ cp a.s b.s $ echo 'package t' > a.go $ go build # go tip # _/tmp/t duplicate "".constants asm: symbol "".constants listed multiple times $ go1.7 build # Go 1.7 $ Notice that a.s and b.s are using file scoped names, so cmd/asm shouldn't reject them.

Even though cmd/asm has properly separated lexer and parser for each input file. The files are sharing the same cmd/internal/obj.Link in order to generate a single object file. Sharing Link means the files are sharing the same symbol table --- which shouldn't be a problem but cmd/asm didn't do anything to make file scoped symbols truly file scoped.

A more comprehensive test case (for amd64): // t.go package main func A() int64 func B() int64 func main() { if A() != 1 || B() != 2 { panic("BUG") } } // a.s TEXT ·A(SB), 7, $0-8 MOVQ ·constants<>(SB), AX MOVQ AX, ret+0(FP) RET DATA ·constants<>+0x0(SB)/8,$1 GLOBL ·constants<>(SB),8,$8 // b.s TEXT ·B(SB), 7, $0-8 MOVQ ·constants<>(SB), AX MOVQ AX, ret+0(FP) RET DATA ·constants<>+0x0(SB)/8,$2 GLOBL ·constants<>(SB),8,$8 It passes under Go 1.7, but fails to build in Go 1.8. And if cmd/asm doesn't properly implement the semantics of file scoped symbols, it won't pass. As this is regression from Go 1.7, label this issue as Go1.8. There are multiple ways to fix this for Go 1.8, but I'm not sure if we want to preserve this property of Go 1.7: in the final binary, there are two symbols named "main.contants", that is, cmd/asm doesn't mangle the two symbols.