cmd/compile: remove support for old-style bounds check calls

This CL rips out the support for old-style assembly stubs.

We need to keep the Go stubs for wasm support.

Change-Id: I23d6d9f2f06be1ded8d22b3e0ef04ff6e252a587
Reviewed-on: https://go-review.googlesource.com/c/go/+/682402
Reviewed-by: Austin Clements <[email protected]>
LUCI-TryBot-Result: Go LUCI <[email protected]>
Reviewed-by: Cuong Manh Le <[email protected]>
Reviewed-by: Michael Knyszek <[email protected]>

Author: randall77

src/cmd/compile/internal/ssa/op.go

@@ -485,53 +485,6 @@ const (
 	BoundsKindCount
 )
 
-// boundsABI determines which register arguments a bounds check call should use. For an [a:b:c] slice, we do:
-//
-//	CMPQ c, cap
-//	JA   fail1
-//	CMPQ b, c
-//	JA   fail2
-//	CMPQ a, b
-//	JA   fail3
-//
-// fail1: CALL panicSlice3Acap (c, cap)
-// fail2: CALL panicSlice3B (b, c)
-// fail3: CALL panicSlice3C (a, b)
-//
-// When we register allocate that code, we want the same register to be used for
-// the first arg of panicSlice3Acap and the second arg to panicSlice3B. That way,
-// initializing that register once will satisfy both calls.
-// That desire ends up dividing the set of bounds check calls into 3 sets. This function
-// determines which set to use for a given panic call.
-// The first arg for set 0 should be the second arg for set 1.
-// The first arg for set 1 should be the second arg for set 2.
-func boundsABI(b int64) int {
-	switch BoundsKind(b) {
-	case BoundsSlice3Alen,
-		BoundsSlice3AlenU,
-		BoundsSlice3Acap,
-		BoundsSlice3AcapU,
-		BoundsConvert:
-		return 0
-	case BoundsSliceAlen,
-		BoundsSliceAlenU,
-		BoundsSliceAcap,
-		BoundsSliceAcapU,
-		BoundsSlice3B,
-		BoundsSlice3BU:
-		return 1
-	case BoundsIndex,
-		BoundsIndexU,
-		BoundsSliceB,
-		BoundsSliceBU,
-		BoundsSlice3C,
-		BoundsSlice3CU:
-		return 2
-	default:
-		panic("bad BoundsKind")
-	}
-}
-
 // Returns the bounds error code needed by the runtime, and
 // whether the x field is signed.
 func (b BoundsKind) Code() (rtabi.BoundsErrorCode, bool) {

src/cmd/compile/internal/ssagen/ssa.go

@@ -184,42 +184,6 @@ func InitConfig() {
 		BoundsCheckFunc[ssa.BoundsSlice3C] = typecheck.LookupRuntimeFunc("goPanicSlice3C")
 		BoundsCheckFunc[ssa.BoundsSlice3CU] = typecheck.LookupRuntimeFunc("goPanicSlice3CU")
 		BoundsCheckFunc[ssa.BoundsConvert] = typecheck.LookupRuntimeFunc("goPanicSliceConvert")
-	} else {
-		BoundsCheckFunc[ssa.BoundsIndex] = typecheck.LookupRuntimeFunc("panicIndex")
-		BoundsCheckFunc[ssa.BoundsIndexU] = typecheck.LookupRuntimeFunc("panicIndexU")
-		BoundsCheckFunc[ssa.BoundsSliceAlen] = typecheck.LookupRuntimeFunc("panicSliceAlen")
-		BoundsCheckFunc[ssa.BoundsSliceAlenU] = typecheck.LookupRuntimeFunc("panicSliceAlenU")
-		BoundsCheckFunc[ssa.BoundsSliceAcap] = typecheck.LookupRuntimeFunc("panicSliceAcap")
-		BoundsCheckFunc[ssa.BoundsSliceAcapU] = typecheck.LookupRuntimeFunc("panicSliceAcapU")
-		BoundsCheckFunc[ssa.BoundsSliceB] = typecheck.LookupRuntimeFunc("panicSliceB")
-		BoundsCheckFunc[ssa.BoundsSliceBU] = typecheck.LookupRuntimeFunc("panicSliceBU")
-		BoundsCheckFunc[ssa.BoundsSlice3Alen] = typecheck.LookupRuntimeFunc("panicSlice3Alen")
-		BoundsCheckFunc[ssa.BoundsSlice3AlenU] = typecheck.LookupRuntimeFunc("panicSlice3AlenU")
-		BoundsCheckFunc[ssa.BoundsSlice3Acap] = typecheck.LookupRuntimeFunc("panicSlice3Acap")
-		BoundsCheckFunc[ssa.BoundsSlice3AcapU] = typecheck.LookupRuntimeFunc("panicSlice3AcapU")
-		BoundsCheckFunc[ssa.BoundsSlice3B] = typecheck.LookupRuntimeFunc("panicSlice3B")
-		BoundsCheckFunc[ssa.BoundsSlice3BU] = typecheck.LookupRuntimeFunc("panicSlice3BU")
-		BoundsCheckFunc[ssa.BoundsSlice3C] = typecheck.LookupRuntimeFunc("panicSlice3C")
-		BoundsCheckFunc[ssa.BoundsSlice3CU] = typecheck.LookupRuntimeFunc("panicSlice3CU")
-		BoundsCheckFunc[ssa.BoundsConvert] = typecheck.LookupRuntimeFunc("panicSliceConvert")
-	}
-	if Arch.LinkArch.PtrSize == 4 {
-		ExtendCheckFunc[ssa.BoundsIndex] = typecheck.LookupRuntimeVar("panicExtendIndex")
-		ExtendCheckFunc[ssa.BoundsIndexU] = typecheck.LookupRuntimeVar("panicExtendIndexU")
-		ExtendCheckFunc[ssa.BoundsSliceAlen] = typecheck.LookupRuntimeVar("panicExtendSliceAlen")
-		ExtendCheckFunc[ssa.BoundsSliceAlenU] = typecheck.LookupRuntimeVar("panicExtendSliceAlenU")
-		ExtendCheckFunc[ssa.BoundsSliceAcap] = typecheck.LookupRuntimeVar("panicExtendSliceAcap")
-		ExtendCheckFunc[ssa.BoundsSliceAcapU] = typecheck.LookupRuntimeVar("panicExtendSliceAcapU")
-		ExtendCheckFunc[ssa.BoundsSliceB] = typecheck.LookupRuntimeVar("panicExtendSliceB")
-		ExtendCheckFunc[ssa.BoundsSliceBU] = typecheck.LookupRuntimeVar("panicExtendSliceBU")
-		ExtendCheckFunc[ssa.BoundsSlice3Alen] = typecheck.LookupRuntimeVar("panicExtendSlice3Alen")
-		ExtendCheckFunc[ssa.BoundsSlice3AlenU] = typecheck.LookupRuntimeVar("panicExtendSlice3AlenU")
-		ExtendCheckFunc[ssa.BoundsSlice3Acap] = typecheck.LookupRuntimeVar("panicExtendSlice3Acap")
-		ExtendCheckFunc[ssa.BoundsSlice3AcapU] = typecheck.LookupRuntimeVar("panicExtendSlice3AcapU")
-		ExtendCheckFunc[ssa.BoundsSlice3B] = typecheck.LookupRuntimeVar("panicExtendSlice3B")
-		ExtendCheckFunc[ssa.BoundsSlice3BU] = typecheck.LookupRuntimeVar("panicExtendSlice3BU")
-		ExtendCheckFunc[ssa.BoundsSlice3C] = typecheck.LookupRuntimeVar("panicExtendSlice3C")
-		ExtendCheckFunc[ssa.BoundsSlice3CU] = typecheck.LookupRuntimeVar("panicExtendSlice3CU")
 	}
 
 	// Wasm (all asm funcs with special ABIs)
@@ -7758,7 +7722,4 @@ func SpillSlotAddr(spill ssa.Spill, baseReg int16, extraOffset int64) obj.Addr {
 	}
 }
 
-var (
-	BoundsCheckFunc [ssa.BoundsKindCount]*obj.LSym
-	ExtendCheckFunc [ssa.BoundsKindCount]*obj.LSym
-)
+var BoundsCheckFunc [ssa.BoundsKindCount]*obj.LSym

src/runtime/panic.go

@@ -103,9 +103,8 @@ func panicCheck2(err string) {
 // these (they always look like they're called from the runtime).
 // Hence, for these, we just check for clearly bad runtime conditions.
 //
-// The panic{Index,Slice} functions are implemented in assembly and tail call
-// to the goPanic{Index,Slice} functions below. This is done so we can use
-// a space-minimal register calling convention.
+// The goPanic{Index,Slice} functions are only used by wasm. All the other architectures
+// use panic{Bounds,Extend} in assembly, which then call to panicBounds{64,32,32X}.
 
 // failures in the comparisons for s[x], 0 <= x < y (y == len(s))
 //
@@ -205,28 +204,10 @@ func goPanicSliceConvert(x int, y int) {
 	panic(boundsError{x: int64(x), signed: true, y: y, code: abi.BoundsConvert})
 }
 
-// Implemented in assembly, as they take arguments in registers.
-// Declared here to mark them as ABIInternal.
-func panicIndex(x int, y int)
-func panicIndexU(x uint, y int)
-func panicSliceAlen(x int, y int)
-func panicSliceAlenU(x uint, y int)
-func panicSliceAcap(x int, y int)
-func panicSliceAcapU(x uint, y int)
-func panicSliceB(x int, y int)
-func panicSliceBU(x uint, y int)
-func panicSlice3Alen(x int, y int)
-func panicSlice3AlenU(x uint, y int)
-func panicSlice3Acap(x int, y int)
-func panicSlice3AcapU(x uint, y int)
-func panicSlice3B(x int, y int)
-func panicSlice3BU(x uint, y int)
-func panicSlice3C(x int, y int)
-func panicSlice3CU(x uint, y int)
-func panicSliceConvert(x int, y int)
-
+// Implemented in assembly. Declared here to mark them as ABIInternal.
 func panicBounds() // in asm_GOARCH.s files, called from generated code
 func panicExtend() // in asm_GOARCH.s files, called from generated code (on 32-bit archs)
+
 func panicBounds64(pc uintptr, regs *[16]int64) { // called from panicBounds on 64-bit archs
 	f := findfunc(pc)
 	v := pcdatavalue(f, abi.PCDATA_PanicBounds, pc-1)