runtime/cgo: declare crosscall2 frame using TEXT for amd64 and 386

Use TEXT pseudo-instruction to adjust SP instead of a SUB instruction
so that the assembler knows how to fill in the pcsp table and the frame
description entry correctly.

Updates #21569

Change-Id: I436c840b2af99bbb3042ecd38a7d7c1ab4d7372a
Reviewed-on: https://go-review.googlesource.com/70937
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>

src/runtime/cgo/asm_386.s

@@ -7,26 +7,23 @@
 // Called by C code generated by cmd/cgo.
 // func crosscall2(fn func(a unsafe.Pointer, n int32, ctxt uintptr), a unsafe.Pointer, n int32, ctxt uintptr)
 // Saves C callee-saved registers and calls fn with three arguments.
-TEXT crosscall2(SB),NOSPLIT,$0
-	PUSHL	BP
-	MOVL	SP, BP
-	PUSHL	BX
-	PUSHL	SI
-	PUSHL	DI
+TEXT crosscall2(SB),NOSPLIT,$28-16
+	MOVL BP, 24(SP)
+	MOVL BX, 20(SP)
+	MOVL SI, 16(SP)
+	MOVL DI, 12(SP)
 
-	SUBL	$12, SP
-	MOVL	20(BP), AX
+	MOVL	ctxt+12(FP), AX
 	MOVL	AX, 8(SP)
-	MOVL	16(BP), AX
+	MOVL	n+8(FP), AX
 	MOVL	AX, 4(SP)
-	MOVL	12(BP), AX
+	MOVL	a+4(FP), AX
 	MOVL	AX, 0(SP)
-	MOVL	8(BP), AX
+	MOVL	fn+0(FP), AX
 	CALL	AX
-	ADDL	$12, SP
 
-	POPL	DI
-	POPL	SI
-	POPL	BX
-	POPL	BP
+	MOVL 12(SP), DI
+	MOVL 16(SP), SI
+	MOVL 20(SP), BX
+	MOVL 24(SP), BP
 	RET

src/runtime/cgo/asm_amd64.s

@@ -7,14 +7,12 @@
 // Called by C code generated by cmd/cgo.
 // func crosscall2(fn func(a unsafe.Pointer, n int32, ctxt uintptr), a unsafe.Pointer, n int32, ctxt uintptr)
 // Saves C callee-saved registers and calls fn with three arguments.
-TEXT crosscall2(SB),NOSPLIT,$0
 #ifndef GOOS_windows
-	SUBQ	$0x58, SP	/* keeps stack pointer 32-byte aligned */
+TEXT crosscall2(SB),NOSPLIT,$0x50-0 /* keeps stack pointer 32-byte aligned */
 #else
-	SUBQ	$0x118, SP	/* also need to save xmm6 - xmm15 */
+TEXT crosscall2(SB),NOSPLIT,$0x110-0 /* also need to save xmm6 - xmm15 */
 #endif
 	MOVQ	BX, 0x18(SP)
-	MOVQ	BP, 0x20(SP)
 	MOVQ	R12, 0x28(SP)
 	MOVQ	R13, 0x30(SP)
 	MOVQ	R14, 0x38(SP)
@@ -62,15 +60,9 @@ TEXT crosscall2(SB),NOSPLIT,$0
 #endif
 
 	MOVQ	0x18(SP), BX
-	MOVQ	0x20(SP), BP
 	MOVQ	0x28(SP), R12
 	MOVQ	0x30(SP), R13
 	MOVQ	0x38(SP), R14
 	MOVQ	0x40(SP), R15
 	
-#ifndef GOOS_windows
-	ADDQ	$0x58, SP
-#else
-	ADDQ	$0x118, SP
-#endif
 	RET