[dev.regabi] cmd/internal/obj/x86: use g register in stack bounds check

In ABIInternal context, we can directly use the g register for
stack bounds check.

Change-Id: I8b1073a3343984a6cd76cf5734ddc4a8cd5dc73f
Reviewed-on: https://go-review.googlesource.com/c/go/+/289711
Trust: Cherry Zhang <cherryyz@google.com>
Run-TryBot: Cherry Zhang <cherryyz@google.com>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: David Chase <drchase@google.com>

diff --git a/src/cmd/internal/obj/x86/obj6.go b/src/cmd/internal/obj/x86/obj6.go
index 1674db626fbb19424e63424f285a989274e5b024..84de58a4c4b87290a1437b82b4db2c5e40599b9b 100644 (file)
--- a/src/cmd/internal/obj/x86/obj6.go
+++ b/src/cmd/internal/obj/x86/obj6.go
@@ -637,13 +637,19 @@ func preprocess(ctxt *obj.Link, cursym *obj.LSym, newprog obj.ProgAlloc) {
                }
        }
 
+       var regg int16
        if !p.From.Sym.NoSplit() || (p.From.Sym.Wrapper() && !p.From.Sym.ABIWrapper()) {
-               p = obj.Appendp(p, newprog)
-               p = load_g_cx(ctxt, p, newprog) // load g into CX
+               if ctxt.Arch.Family == sys.AMD64 && objabi.Regabi_enabled != 0 && cursym.ABI() == obj.ABIInternal {
+                       regg = REGG // use the g register directly in ABIInternal
+               } else {
+                       p = obj.Appendp(p, newprog)
+                       p = load_g_cx(ctxt, p, newprog) // load g into CX
+                       regg = REG_CX
+               }
        }
 
        if !cursym.Func().Text.From.Sym.NoSplit() {
-               p = stacksplit(ctxt, cursym, p, newprog, autoffset, int32(textarg)) // emit split check
+               p = stacksplit(ctxt, cursym, p, newprog, autoffset, int32(textarg), regg) // emit split check
        }
 
        // Delve debugger would like the next instruction to be noted as the end of the function prologue.
@@ -695,7 +701,7 @@ func preprocess(ctxt *obj.Link, cursym *obj.LSym, newprog obj.ProgAlloc) {
                //   g._panic.argp = bottom-of-frame
                // }
                //
-               //      MOVQ g_panic(CX), BX
+               //      MOVQ g_panic(g), BX
                //      TESTQ BX, BX
                //      JNE checkargp
                // end:
@@ -718,7 +724,7 @@ func preprocess(ctxt *obj.Link, cursym *obj.LSym, newprog obj.ProgAlloc) {
                p = obj.Appendp(p, newprog)
                p.As = AMOVQ
                p.From.Type = obj.TYPE_MEM
-               p.From.Reg = REG_CX
+               p.From.Reg = regg
                p.From.Offset = 4 * int64(ctxt.Arch.PtrSize) // g_panic
                p.To.Type = obj.TYPE_REG
                p.To.Reg = REG_BX
@@ -969,9 +975,9 @@ func load_g_cx(ctxt *obj.Link, p *obj.Prog, newprog obj.ProgAlloc) *obj.Prog {
 
 // Append code to p to check for stack split.
 // Appends to (does not overwrite) p.
-// Assumes g is in CX.
+// Assumes g is in rg.
 // Returns last new instruction.
-func stacksplit(ctxt *obj.Link, cursym *obj.LSym, p *obj.Prog, newprog obj.ProgAlloc, framesize int32, textarg int32) *obj.Prog {
+func stacksplit(ctxt *obj.Link, cursym *obj.LSym, p *obj.Prog, newprog obj.ProgAlloc, framesize int32, textarg int32, rg int16) *obj.Prog {
        cmp := ACMPQ
        lea := ALEAQ
        mov := AMOVQ
@@ -993,7 +999,8 @@ func stacksplit(ctxt *obj.Link, cursym *obj.LSym, p *obj.Prog, newprog obj.ProgA
                p.As = cmp
                p.From.Type = obj.TYPE_REG
                p.From.Reg = REG_SP
-               indir_cx(ctxt, &p.To)
+               p.To.Type = obj.TYPE_MEM
+               p.To.Reg = rg
                p.To.Offset = 2 * int64(ctxt.Arch.PtrSize) // G.stackguard0
                if cursym.CFunc() {
                        p.To.Offset = 3 * int64(ctxt.Arch.PtrSize) // G.stackguard1
@@ -1021,7 +1028,8 @@ func stacksplit(ctxt *obj.Link, cursym *obj.LSym, p *obj.Prog, newprog obj.ProgA
                p.As = cmp
                p.From.Type = obj.TYPE_REG
                p.From.Reg = REG_AX
-               indir_cx(ctxt, &p.To)
+               p.To.Type = obj.TYPE_MEM
+               p.To.Reg = rg
                p.To.Offset = 2 * int64(ctxt.Arch.PtrSize) // G.stackguard0
                if cursym.CFunc() {
                        p.To.Offset = 3 * int64(ctxt.Arch.PtrSize) // G.stackguard1
@@ -1047,7 +1055,8 @@ func stacksplit(ctxt *obj.Link, cursym *obj.LSym, p *obj.Prog, newprog obj.ProgA
                p = obj.Appendp(p, newprog)
 
                p.As = mov
-               indir_cx(ctxt, &p.From)
+               p.From.Type = obj.TYPE_MEM
+               p.From.Reg = rg
                p.From.Offset = 2 * int64(ctxt.Arch.PtrSize) // G.stackguard0
                if cursym.CFunc() {
                        p.From.Offset = 3 * int64(ctxt.Arch.PtrSize) // G.stackguard1