From 8af7fac5a1d2b3881f8f435d77adfcef6a07bedc Mon Sep 17 00:00:00 2001 From: Austin Clements Date: Mon, 18 Apr 2022 13:39:52 -0400 Subject: [PATCH] internal/sys: add LR and fixed frame size to sys.Arch Storing this information in the Arch eliminates some code duplication between the compiler and linker. This information is entirely determined by the Arch, so the current approach of attaching it to an entire Ctxt is a little silly. This will also make it easier to use this information from tests. The next CL will be a rote refactoring to eliminate the Ctxt.FixedFrameSize methods. Change-Id: I315c524fa66a0ea99f63ae5a2a6fdc367d843bad Reviewed-on: https://go-review.googlesource.com/c/go/+/400818 Run-TryBot: Austin Clements Reviewed-by: Cherry Mui TryBot-Result: Gopher Robot --- src/cmd/internal/obj/link.go | 11 +- src/cmd/internal/sys/arch.go | 252 +++++++++++++++++------------- src/cmd/link/internal/ld/dwarf.go | 2 +- src/cmd/link/internal/ld/lib.go | 8 +- src/cmd/link/internal/ld/link.go | 12 +- 5 files changed, 152 insertions(+), 133 deletions(-) diff --git a/src/cmd/internal/obj/link.go b/src/cmd/internal/obj/link.go index dc06a3aa11..12a4c94e24 100644 --- a/src/cmd/internal/obj/link.go +++ b/src/cmd/internal/obj/link.go @@ -989,16 +989,7 @@ func (fi *FuncInfo) UnspillRegisterArgs(last *Prog, pa ProgAlloc) *Prog { // on the stack in the function prologue and so always have a pointer between // the hardware stack pointer and the local variable area. func (ctxt *Link) FixedFrameSize() int64 { - switch ctxt.Arch.Family { - case sys.AMD64, sys.I386, sys.Wasm: - return 0 - case sys.PPC64: - // PIC code on ppc64le requires 32 bytes of stack, and it's easier to - // just use that much stack always on ppc64x. - return int64(4 * ctxt.Arch.PtrSize) - default: - return int64(ctxt.Arch.PtrSize) - } + return ctxt.Arch.FixedFrameSize } // LinkArch is the definition of a single architecture. diff --git a/src/cmd/internal/sys/arch.go b/src/cmd/internal/sys/arch.go index 84ed35ba8d..5886b42e51 100644 --- a/src/cmd/internal/sys/arch.go +++ b/src/cmd/internal/sys/arch.go @@ -56,6 +56,18 @@ type Arch struct { // CanJumpTable reports whether the backend can handle // compiling a jump table. CanJumpTable bool + + // HasLR indicates that this architecture uses a link register + // for calls. + HasLR bool + + // FixedFrameSize is the smallest possible offset from the + // hardware stack pointer to a local variable on the stack. + // Architectures that use a link register save its value on + // the stack in the function prologue and so always have a + // pointer between the hardware stack pointer and the local + // variable area. + FixedFrameSize int64 } // InFamily reports whether a is a member of any of the specified @@ -70,103 +82,121 @@ func (a *Arch) InFamily(xs ...ArchFamily) bool { } var Arch386 = &Arch{ - Name: "386", - Family: I386, - ByteOrder: binary.LittleEndian, - PtrSize: 4, - RegSize: 4, - MinLC: 1, - Alignment: 1, - CanMergeLoads: true, + Name: "386", + Family: I386, + ByteOrder: binary.LittleEndian, + PtrSize: 4, + RegSize: 4, + MinLC: 1, + Alignment: 1, + CanMergeLoads: true, + HasLR: false, + FixedFrameSize: 0, } var ArchAMD64 = &Arch{ - Name: "amd64", - Family: AMD64, - ByteOrder: binary.LittleEndian, - PtrSize: 8, - RegSize: 8, - MinLC: 1, - Alignment: 1, - CanMergeLoads: true, - CanJumpTable: true, + Name: "amd64", + Family: AMD64, + ByteOrder: binary.LittleEndian, + PtrSize: 8, + RegSize: 8, + MinLC: 1, + Alignment: 1, + CanMergeLoads: true, + CanJumpTable: true, + HasLR: false, + FixedFrameSize: 0, } var ArchARM = &Arch{ - Name: "arm", - Family: ARM, - ByteOrder: binary.LittleEndian, - PtrSize: 4, - RegSize: 4, - MinLC: 4, - Alignment: 4, // TODO: just for arm5? - CanMergeLoads: false, + Name: "arm", + Family: ARM, + ByteOrder: binary.LittleEndian, + PtrSize: 4, + RegSize: 4, + MinLC: 4, + Alignment: 4, // TODO: just for arm5? + CanMergeLoads: false, + HasLR: true, + FixedFrameSize: 4, // LR } var ArchARM64 = &Arch{ - Name: "arm64", - Family: ARM64, - ByteOrder: binary.LittleEndian, - PtrSize: 8, - RegSize: 8, - MinLC: 4, - Alignment: 1, - CanMergeLoads: true, + Name: "arm64", + Family: ARM64, + ByteOrder: binary.LittleEndian, + PtrSize: 8, + RegSize: 8, + MinLC: 4, + Alignment: 1, + CanMergeLoads: true, + HasLR: true, + FixedFrameSize: 8, // LR } var ArchLoong64 = &Arch{ - Name: "loong64", - Family: Loong64, - ByteOrder: binary.LittleEndian, - PtrSize: 8, - RegSize: 8, - MinLC: 4, - Alignment: 8, // Unaligned accesses are not guaranteed to be fast - CanMergeLoads: false, + Name: "loong64", + Family: Loong64, + ByteOrder: binary.LittleEndian, + PtrSize: 8, + RegSize: 8, + MinLC: 4, + Alignment: 8, // Unaligned accesses are not guaranteed to be fast + CanMergeLoads: false, + HasLR: true, + FixedFrameSize: 8, // LR } var ArchMIPS = &Arch{ - Name: "mips", - Family: MIPS, - ByteOrder: binary.BigEndian, - PtrSize: 4, - RegSize: 4, - MinLC: 4, - Alignment: 4, - CanMergeLoads: false, + Name: "mips", + Family: MIPS, + ByteOrder: binary.BigEndian, + PtrSize: 4, + RegSize: 4, + MinLC: 4, + Alignment: 4, + CanMergeLoads: false, + HasLR: true, + FixedFrameSize: 4, // LR } var ArchMIPSLE = &Arch{ - Name: "mipsle", - Family: MIPS, - ByteOrder: binary.LittleEndian, - PtrSize: 4, - RegSize: 4, - MinLC: 4, - Alignment: 4, - CanMergeLoads: false, + Name: "mipsle", + Family: MIPS, + ByteOrder: binary.LittleEndian, + PtrSize: 4, + RegSize: 4, + MinLC: 4, + Alignment: 4, + CanMergeLoads: false, + HasLR: true, + FixedFrameSize: 4, // LR } var ArchMIPS64 = &Arch{ - Name: "mips64", - Family: MIPS64, - ByteOrder: binary.BigEndian, - PtrSize: 8, - RegSize: 8, - MinLC: 4, - Alignment: 8, - CanMergeLoads: false, + Name: "mips64", + Family: MIPS64, + ByteOrder: binary.BigEndian, + PtrSize: 8, + RegSize: 8, + MinLC: 4, + Alignment: 8, + CanMergeLoads: false, + HasLR: true, + FixedFrameSize: 8, // LR } var ArchMIPS64LE = &Arch{ - Name: "mips64le", - Family: MIPS64, - ByteOrder: binary.LittleEndian, - PtrSize: 8, - RegSize: 8, - MinLC: 4, - Alignment: 8, - CanMergeLoads: false, + Name: "mips64le", + Family: MIPS64, + ByteOrder: binary.LittleEndian, + PtrSize: 8, + RegSize: 8, + MinLC: 4, + Alignment: 8, + CanMergeLoads: false, + HasLR: true, + FixedFrameSize: 8, // LR } var ArchPPC64 = &Arch{ @@ -178,50 +208,62 @@ var ArchPPC64 = &Arch{ MinLC: 4, Alignment: 1, CanMergeLoads: false, + HasLR: true, + // PIC code on ppc64le requires 32 bytes of stack, and it's + // easier to just use that much stack always. + FixedFrameSize: 4 * 8, } var ArchPPC64LE = &Arch{ - Name: "ppc64le", - Family: PPC64, - ByteOrder: binary.LittleEndian, - PtrSize: 8, - RegSize: 8, - MinLC: 4, - Alignment: 1, - CanMergeLoads: true, + Name: "ppc64le", + Family: PPC64, + ByteOrder: binary.LittleEndian, + PtrSize: 8, + RegSize: 8, + MinLC: 4, + Alignment: 1, + CanMergeLoads: true, + HasLR: true, + FixedFrameSize: 4 * 8, } var ArchRISCV64 = &Arch{ - Name: "riscv64", - Family: RISCV64, - ByteOrder: binary.LittleEndian, - PtrSize: 8, - RegSize: 8, - MinLC: 4, - Alignment: 8, // riscv unaligned loads work, but are really slow (trap + simulated by OS) - CanMergeLoads: false, + Name: "riscv64", + Family: RISCV64, + ByteOrder: binary.LittleEndian, + PtrSize: 8, + RegSize: 8, + MinLC: 4, + Alignment: 8, // riscv unaligned loads work, but are really slow (trap + simulated by OS) + CanMergeLoads: false, + HasLR: true, + FixedFrameSize: 8, // LR } var ArchS390X = &Arch{ - Name: "s390x", - Family: S390X, - ByteOrder: binary.BigEndian, - PtrSize: 8, - RegSize: 8, - MinLC: 2, - Alignment: 1, - CanMergeLoads: true, + Name: "s390x", + Family: S390X, + ByteOrder: binary.BigEndian, + PtrSize: 8, + RegSize: 8, + MinLC: 2, + Alignment: 1, + CanMergeLoads: true, + HasLR: true, + FixedFrameSize: 8, // LR } var ArchWasm = &Arch{ - Name: "wasm", - Family: Wasm, - ByteOrder: binary.LittleEndian, - PtrSize: 8, - RegSize: 8, - MinLC: 1, - Alignment: 1, - CanMergeLoads: false, + Name: "wasm", + Family: Wasm, + ByteOrder: binary.LittleEndian, + PtrSize: 8, + RegSize: 8, + MinLC: 1, + Alignment: 1, + CanMergeLoads: false, + HasLR: false, + FixedFrameSize: 0, } var Archs = [...]*Arch{ diff --git a/src/cmd/link/internal/ld/dwarf.go b/src/cmd/link/internal/ld/dwarf.go index 2e209d0c6b..6ed9697aec 100644 --- a/src/cmd/link/internal/ld/dwarf.go +++ b/src/cmd/link/internal/ld/dwarf.go @@ -1360,7 +1360,7 @@ func (d *dwctxt) writeframes(fs loader.Sym) dwarfSecInfo { fsu := d.ldr.MakeSymbolUpdater(fs) fsu.SetType(sym.SDWARFSECT) isdw64 := isDwarf64(d.linkctxt) - haslr := haslinkregister(d.linkctxt) + haslr := d.linkctxt.Arch.HasLR // Length field is 4 bytes on Dwarf32 and 12 bytes on Dwarf64 lengthFieldSize := int64(4) diff --git a/src/cmd/link/internal/ld/lib.go b/src/cmd/link/internal/ld/lib.go index 4295bb8656..7104a3c8b6 100644 --- a/src/cmd/link/internal/ld/lib.go +++ b/src/cmd/link/internal/ld/lib.go @@ -2349,12 +2349,8 @@ type chain struct { limit int // limit on entry to sym } -func haslinkregister(ctxt *Link) bool { - return ctxt.FixedFrameSize() != 0 -} - func callsize(ctxt *Link) int { - if haslinkregister(ctxt) { + if ctxt.Arch.HasLR { return 0 } return ctxt.Arch.RegSize @@ -2554,7 +2550,7 @@ func (sc *stkChk) print(ch *chain, limit int) { } } else { sc.print(ch.up, ch.limit+callsize(ctxt)) - if !haslinkregister(ctxt) { + if !ctxt.Arch.HasLR { fmt.Printf("\t%d\ton entry to %s\n", ch.limit, name) } } diff --git a/src/cmd/link/internal/ld/link.go b/src/cmd/link/internal/ld/link.go index 64d18bd62c..f1b5f4d223 100644 --- a/src/cmd/link/internal/ld/link.go +++ b/src/cmd/link/internal/ld/link.go @@ -33,7 +33,6 @@ package ld import ( "bufio" "cmd/internal/objabi" - "cmd/internal/sys" "cmd/link/internal/loader" "cmd/link/internal/sym" "debug/elf" @@ -108,16 +107,7 @@ type cgodata struct { // on the stack in the function prologue and so always have a pointer between // the hardware stack pointer and the local variable area. func (ctxt *Link) FixedFrameSize() int64 { - switch ctxt.Arch.Family { - case sys.AMD64, sys.I386: - return 0 - case sys.PPC64: - // PIC code on ppc64le requires 32 bytes of stack, and it's easier to - // just use that much stack always on ppc64x. - return int64(4 * ctxt.Arch.PtrSize) - default: - return int64(ctxt.Arch.PtrSize) - } + return ctxt.Arch.FixedFrameSize } func (ctxt *Link) Logf(format string, args ...interface{}) {