From dbd1e42ef227bf55e9356b2d1a1cbde1fbec0e82 Mon Sep 17 00:00:00 2001
From: Noam Preil <noam@pixelhero.dev>
Date: Sun, 9 Aug 2020 19:44:16 -0400
Subject: [PATCH] CBE: Sorta working intcasts?

---
 src-self-hosted/codegen/c.zig | 27 ++++++++++++++++++--------
 test/stage2/cbe.zig           | 36 +++++++++++++++++++++++++++++++++++
 2 files changed, 55 insertions(+), 8 deletions(-)

diff --git a/src-self-hosted/codegen/c.zig b/src-self-hosted/codegen/c.zig
index 591e47967e..907bbccda1 100644
--- a/src-self-hosted/codegen/c.zig
+++ b/src-self-hosted/codegen/c.zig
@@ -117,6 +117,8 @@ fn genFn(file: *C, decl: *Decl) !void {
                 .dbg_stmt => try genDbgStmt(file, inst.castTag(.dbg_stmt).?, decl),
                 .breakpoint => try genBreak(file, inst.castTag(.breakpoint).?, decl),
                 .unreach => try genUnreach(file, inst.castTag(.unreach).?, decl),
+                // This will be handled correctly later?
+                .intcast => {},
                 else => |e| return file.fail(decl.src(), "TODO implement C codegen for {}", .{e}),
             }
         }
@@ -129,6 +131,20 @@ fn genRet(file: *C, inst: *Inst.UnOp, decl: *Decl, expected_return_type: Type) !
     return file.fail(decl.src(), "TODO return {}", .{expected_return_type});
 }
 
+fn genIntCast(file: *C, inst: *Inst.UnOp, decl: *Decl, argdex: *usize) !void {
+    const op = inst.operand;
+    const writer = file.main.writer();
+    try writer.writeByte('(');
+    try renderType(file, writer, inst.base.ty, decl.src());
+    try writer.writeByte(')');
+    if (op.castTag(.arg)) |_| {
+        try writer.print("arg{}", .{argdex.*});
+        argdex.* += 1;
+    } else {
+        return file.fail(decl.src(), "TODO intcast {} to {}", .{ op, inst.base.ty });
+    }
+}
+
 fn genCall(file: *C, inst: *Inst.Call, decl: *Decl) !void {
     const writer = file.main.writer();
     const header = file.header.writer();
@@ -196,6 +212,8 @@ fn genAsm(file: *C, as: *Inst.Assembly, decl: *Decl, argdex: *usize) !void {
             } else if (arg.castTag(.arg)) |inst| {
                 try writer.print("arg{}", .{argdex.*});
                 argdex.* += 1;
+            } else if (arg.castTag(.intcast)) |inst| {
+                try genIntCast(file, inst, decl, argdex);
             } else {
                 return file.fail(decl.src(), "TODO non-constant inline asm args ({})", .{arg.tag});
             }
@@ -220,14 +238,7 @@ fn genAsm(file: *C, as: *Inst.Assembly, decl: *Decl, argdex: *usize) !void {
                 if (index > 0) {
                     try writer.writeAll(", ");
                 }
-                try writer.writeAll("\"\"(");
-                if (arg.tag == .constant or arg.tag == .arg) {
-                    try writer.print("{}_constant", .{reg});
-                } else {
-                    // This is blocked by the earlier test
-                    unreachable;
-                }
-                try writer.writeByte(')');
+                try writer.print("\"\"({}_constant)", .{reg});
             } else {
                 // This is blocked by the earlier test
                 unreachable;
diff --git a/test/stage2/cbe.zig b/test/stage2/cbe.zig
index 59bc062b74..4b35286f94 100644
--- a/test/stage2/cbe.zig
+++ b/test/stage2/cbe.zig
@@ -100,4 +100,40 @@ pub fn addCases(ctx: *TestContext) !void {
         \\}
         \\
     );
+    ctx.c("exit with u8 parameter", linux_x64,
+        \\export fn _start() noreturn {
+        \\    exit(0);
+        \\}
+        \\
+        \\fn exit(code: u8) noreturn {
+        \\    asm volatile ("syscall"
+        \\        :
+        \\        : [number] "{rax}" (231),
+        \\          [arg1] "{rdi}" (code)
+        \\    );
+        \\    unreachable;
+        \\}
+        \\
+    ,
+        \\#include <stddef.h>
+        \\#include <stdint.h>
+        \\
+        \\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) {
+        \\    exit(0);
+        \\}
+        \\
+        \\zig_noreturn void exit(uint8_t arg0) {
+        \\    register size_t rax_constant __asm__("rax") = 231;
+        \\    register size_t rdi_constant __asm__("rdi") = (size_t)arg0;
+        \\    __asm volatile ("syscall" :: ""(rax_constant), ""(rdi_constant));
+        \\    zig_unreachable();
+        \\}
+        \\
+    );
 }