From 9bb19a090ea1d1d47b214974d5e18e11ef4adb85 Mon Sep 17 00:00:00 2001
From: Tom Maenan Read Cutting <readcuttingt@gmail.com>
Date: Thu, 10 Mar 2022 22:17:07 +0000
Subject: [PATCH] std: Add elf.EM, coff.MachineType to Target.CPU.Arch
 conversions

target.Arch already supports finding the correct encoding for either
target, so being able to do the inverse has use cases for when parsing
files of an unknown target (i.e. for zar).
---
 lib/std/coff.zig | 15 +++++++++++++++
 lib/std/elf.zig  | 32 +++++++++++++++++++++++++++++++-
 2 files changed, 46 insertions(+), 1 deletion(-)

diff --git a/lib/std/coff.zig b/lib/std/coff.zig
index 2bf0b1c44e..a2da0552be 100644
--- a/lib/std/coff.zig
+++ b/lib/std/coff.zig
@@ -62,6 +62,21 @@ pub const MachineType = enum(u16) {
     Thumb = 0x1c2,
     /// MIPS little-endian WCE v2
     WCEMIPSV2 = 0x169,
+
+    pub fn toTargetCpuArch(machine_type: MachineType) ?std.Target.Cpu.Arch {
+        return switch (machine_type) {
+            .ARM => .arm,
+            .POWERPC => .powerpc,
+            .RISCV32 => .riscv32,
+            .Thumb => .thumb,
+            .I386 => .i386,
+            .ARM64 => .aarch64,
+            .RISCV64 => .riscv64,
+            .X64 => .x86_64,
+            // there's cases we don't (yet) handle
+            else => null,
+        };
+    }
 };
 
 // OptionalHeader.magic values
diff --git a/lib/std/elf.zig b/lib/std/elf.zig
index 6c3b748c58..84001ec1c9 100644
--- a/lib/std/elf.zig
+++ b/lib/std/elf.zig
@@ -1481,6 +1481,36 @@ pub const EM = enum(u16) {
     _BPF = 247,
 
     _,
+
+    pub fn toTargetCpuArch(em: EM) ?std.Target.Cpu.Arch {
+        return switch (em) {
+            ._AVR => .avr,
+            ._MSP430 => .msp430,
+            ._ARC => .arc,
+            ._ARM => .arm,
+            ._HEXAGON => .hexagon,
+            ._68K => .m68k,
+            ._MIPS => .mips,
+            ._MIPS_RS3_LE => .mipsel,
+            ._PPC => .powerpc,
+            ._SPARC => .sparc,
+            ._386 => .i386,
+            ._XCORE => .xcore,
+            ._CSR_KALIMBA => .kalimba,
+            ._LANAI => .lanai,
+            ._AARCH64 => .aarch64,
+            ._PPC64 => .powerpc64,
+            ._RISCV => .riscv64,
+            ._X86_64 => .x86_64,
+            ._BPF => .bpfel,
+            ._SPARCV9 => .sparcv9,
+            ._S390 => .s390x,
+            ._SPU_2 => .spu_2,
+            // there's many cases we don't (yet) handle, or will never have a
+            // zig target cpu arch equivalent (such as null).
+            else => null,
+        };
+    }
 };
 
 /// Section data should be writable during execution.
@@ -1681,7 +1711,7 @@ pub const R_X86_64_TLSDESC = 36;
 pub const R_X86_64_IRELATIVE = 37;
 /// 64-bit adjust by program base
 pub const R_X86_64_RELATIVE64 = 38;
-/// 39 Reserved was R_X86_64_PC32_BND 
+/// 39 Reserved was R_X86_64_PC32_BND
 /// 40 Reserved was R_X86_64_PLT32_BND
 /// Load from 32 bit signed pc relative offset to GOT entry without REX prefix, relaxable
 pub const R_X86_64_GOTPCRELX = 41;