debug/elf,cmd/link: add additional MIPS64 relocation type

Add R_MIPS_PC32 which is a 32 bit PC relative relocation.

These are produced by LLVM on mips64.

Fixes #61974

Change-Id: I7b6c6848e40249e6d5ea474ea53c9d7e3ab23f88
Reviewed-on: https://go-review.googlesource.com/c/go/+/469395
Reviewed-by: Matthew Dempsky <mdempsky@google.com>
Run-TryBot: Joel Sing <joel@sing.id.au>
Reviewed-by: Junxian Zhu <zhujunxian@oss.cipunited.com>
Reviewed-by: Cherry Mui <cherryyz@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>

Author: 4a6f656c

api/next/61974.txt

@@ -0,0 +1,2 @@
+pkg debug/elf, const R_MIPS_PC32 = 248 #61974
+pkg debug/elf, const R_MIPS_PC32 R_MIPS #61974

src/cmd/link/internal/loadelf/ldelf.go

@@ -1018,7 +1018,8 @@ func relSize(arch *sys.Arch, pn string, elftype uint32) (uint8, uint8, error) {
 		MIPS64 | uint32(elf.R_MIPS_CALL16)<<16,
 		MIPS64 | uint32(elf.R_MIPS_GPREL32)<<16,
 		MIPS64 | uint32(elf.R_MIPS_64)<<16,
-		MIPS64 | uint32(elf.R_MIPS_GOT_DISP)<<16:
+		MIPS64 | uint32(elf.R_MIPS_GOT_DISP)<<16,
+		MIPS64 | uint32(elf.R_MIPS_PC32)<<16:
 		return 4, 4, nil
 
 	case LOONG64 | uint32(elf.R_LARCH_SOP_PUSH_PCREL)<<16,

src/debug/elf/elf.go

@@ -2216,6 +2216,8 @@ const (
 	R_MIPS_TLS_TPREL64     R_MIPS = 48 /* TP-relative offset, 64 bit */
 	R_MIPS_TLS_TPREL_HI16  R_MIPS = 49 /* TP-relative offset, high 16 bits */
 	R_MIPS_TLS_TPREL_LO16  R_MIPS = 50 /* TP-relative offset, low 16 bits */
+
+	R_MIPS_PC32 R_MIPS = 248 /* 32 bit PC relative reference */
 )
 
 var rmipsStrings = []intName{
@@ -2267,6 +2269,7 @@ var rmipsStrings = []intName{
 	{48, "R_MIPS_TLS_TPREL64"},
 	{49, "R_MIPS_TLS_TPREL_HI16"},
 	{50, "R_MIPS_TLS_TPREL_LO16"},
+	{248, "R_MIPS_PC32"},
 }
 
 func (i R_MIPS) String() string   { return stringName(uint32(i), rmipsStrings, false) }