CBE: addition and subtraction

2 files changed, 63 insertions, 0 deletions

diff --git a/src/codegen/c.zig b/src/codegen/c.zig
index 5d350f7bd5..99ac0cfe00 100644
--- a/src/codegen/c.zig
+++ b/src/codegen/c.zig
@@ -160,6 +160,8 @@ fn genFn(file: *C, decl: *Decl) !void {
             if (switch (inst.tag) {
                 .assembly => try genAsm(&ctx, inst.castTag(.assembly).?),
                 .call => try genCall(&ctx, inst.castTag(.call).?),
+                .add => try genBinOp(&ctx, inst.cast(Inst.BinOp).?, "+"),
+                .sub => try genBinOp(&ctx, inst.cast(Inst.BinOp).?, "-"),
                 .ret => try genRet(&ctx, inst.castTag(.ret).?),
                 .retvoid => try genRetVoid(&ctx),
                 .arg => try genArg(&ctx),
@@ -207,6 +209,19 @@ fn genIntCast(ctx: *Context, inst: *Inst.UnOp) !?[]u8 {
     return name;
 }
 
+fn genBinOp(ctx: *Context, inst: *Inst.BinOp, comptime operator: []const u8) !?[]u8 {
+    if (inst.base.isUnused())
+        return null;
+    const lhs = ctx.resolveInst(inst.lhs);
+    const rhs = ctx.resolveInst(inst.rhs);
+    const writer = ctx.file.main.writer();
+    const name = try ctx.name();
+    try writer.writeAll(indentation ++ "const ");
+    try renderType(ctx, writer, inst.base.ty);
+    try writer.print(" {} = {} " ++ operator ++ " {};\n", .{ name, lhs, rhs });
+    return name;
+}
+
 fn genCall(ctx: *Context, inst: *Inst.Call) !?[]u8 {
     const writer = ctx.file.main.writer();
     const header = ctx.file.header.writer();
diff --git a/test/stage2/cbe.zig b/test/stage2/cbe.zig
index 2a176e0368..0be5bd8704 100644
--- a/test/stage2/cbe.zig
+++ b/test/stage2/cbe.zig
@@ -147,4 +147,52 @@ pub fn addCases(ctx: *TestContext) !void {
         \\}
         \\
     );
+    ctx.c("exit with u8 arithmetic", linux_x64,
+        \\export fn _start() noreturn {
+        \\    exitMath(1);
+        \\}
+        \\
+        \\fn exitMath(a: u8) noreturn {
+        \\    exit(0 + a - a);
+        \\}
+        \\
+        \\fn exit(code: u8) noreturn {
+        \\    asm volatile ("syscall"
+        \\        :
+        \\        : [number] "{rax}" (231),
+        \\          [arg1] "{rdi}" (code)
+        \\    );
+        \\    unreachable;
+        \\}
+        \\
+    ,
+        \\#include <stddef.h>
+        \\#include <stdint.h>
+        \\
+        \\zig_noreturn void exitMath(uint8_t arg0);
+        \\zig_noreturn void exit(uint8_t arg0);
+        \\
+        \\const char *const exit__anon_0 = "{rax}";
+        \\const char *const exit__anon_1 = "{rdi}";
+        \\const char *const exit__anon_2 = "syscall";
+        \\
+        \\zig_noreturn void _start(void) {
+        \\    exitMath(1);
+        \\}
+        \\
+        \\zig_noreturn void exitMath(uint8_t arg0) {
+        \\    const uint8_t __temp_0 = 0 + arg0;
+        \\    const uint8_t __temp_1 = __temp_0 - arg0;
+        \\    exit(__temp_1);
+        \\}
+        \\
+        \\zig_noreturn void exit(uint8_t arg0) {
+        \\    const size_t __temp_0 = (size_t)arg0;
+        \\    register size_t rax_constant __asm__("rax") = 231;
+        \\    register size_t rdi_constant __asm__("rdi") = __temp_0;
+        \\    __asm volatile ("syscall" :: ""(rax_constant), ""(rdi_constant));
+        \\    zig_unreachable();
+        \\}
+        \\
+    );
 }