cmd/compile: illegal combination ADD $8, ZR, R2 ABCON0 ZREG NONE REG NONE, 4 7 on arm64

[ALTree]

$ gotip version
go version devel go1.25-1647896aa2 Fri Apr 4 23:25:15 2025 -0700 linux/amd64

package p

func F(a, b map[float32]int) int {
	var st *struct {
		n int
		f float32
	}
	return a[0] + b[st.f]
}

$ GOARCH=arm64 gotip build crash.go 

./crash.go:8:2: illegal combination: 00068 (/home/alberto/crash.go:8)	ADD	$8, ZR, R2 ABCON0 ZREG NONE REG NONE, 4 7

cc @randall77

[gabyhelp]

Related Issues

• cmd/compile: GOARCH=arm64 compiler crash: illegal combination #22390 (closed)
• cmd/compile: "illegal combination SRA ADDCON REG REG" on mips #42587 (closed)
• cmd/compile: panic: log2 of 0 on arm64 #38946 (closed)
• cmd/compile: internal compiler error: not lowered: v654, Int64Hi INT32 INT on 32bit GOARCHs #61041 (closed)
• cmd/compile: internal compiler error: FlagConstant op should never make it to codegen #45359 (closed)
• cmd/7g: compiler crash #10320 (closed)
• cmd/compile: missing logical/move instruction for RSP on arm64 #24332 (closed)

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[gopherbot]

Change https://go.dev/cl/663155 mentions this issue: cmd/compile: be more conservative about arm64 insns that can take zero register