| author |  Joachim Schmidt <joachim.schmidt557@outlook.com> 2021-03-27 22:23:14+01:00 |
| committer |  Jakub Konka <kubkon@jakubkonka.com> 2021-03-31 23:27:50+02:00 |
| log | 1b657e6e41bcaf362d1cc9455c17e06e57973554 |
| tree | 796f29c590abe7d5dc5d0ab5ad195ab8a890e7d0 |
| parent | e088a17f56a154ecc43c36e8308833d657e6f43e |
stage2 codegen: Make sure function return value is in a callee
preserved register2 files changed, 51 insertions(+), 0 deletions(-)
src
test
stage2
src/codegen.zig+10
| ... | @@ -2194,6 +2194,16 @@ fn Function(comptime arch: std.Target.Cpu.Arch) type { | ... | @@ -2194,6 +2194,16 @@ fn Function(comptime arch: std.Target.Cpu.Arch) type { |
| 2194 | unreachable; | 2194 | unreachable; |
| 2195 | } | 2195 | } |
| 2196 | 2196 | ||
| 2197 | switch (info.return_value) { | ||
| 2198 | .register => |reg| { | ||
| 2199 | if (Register.allocIndex(reg) == null) { | ||
| 2200 | // Save function return value in a callee saved register | ||
| 2201 | return try self.copyToNewRegister(&inst.base, info.return_value); | ||
| 2202 | } | ||
| 2203 | }, | ||
| 2204 | else => {}, | ||
| 2205 | } | ||
| 2206 | |||
| 2197 | return info.return_value; | 2207 | return info.return_value; |
| 2198 | } | 2208 | } |
| 2199 | 2209 |
test/stage2/arm.zig+41
| ... | @@ -378,4 +378,45 @@ pub fn addCases(ctx: *TestContext) !void { | ... | @@ -378,4 +378,45 @@ pub fn addCases(ctx: *TestContext) !void { |
| 378 | "", | 378 | "", |
| 379 | ); | 379 | ); |
| 380 | } | 380 | } |
| 381 | |||
| 382 | { | ||
| 383 | var case = ctx.exe("save function return values in callee preserved register", linux_arm); | ||
| 384 | // Here, it is necessary to save the result of bar() into a | ||
| 385 | // callee preserved register, otherwise it will be overwritten | ||
| 386 | // by the first parameter to baz. | ||
| 387 | case.addCompareOutput( | ||
| 388 | \\export fn _start() noreturn { | ||
| 389 | \\ assert(foo() == 43); | ||
| 390 | \\ exit(); | ||
| 391 | \\} | ||
| 392 | \\ | ||
| 393 | \\fn foo() u32 { | ||
| 394 | \\ return bar() + baz(42); | ||
| 395 | \\} | ||
| 396 | \\ | ||
| 397 | \\fn bar() u32 { | ||
| 398 | \\ return 1; | ||
| 399 | \\} | ||
| 400 | \\ | ||
| 401 | \\fn baz(x: u32) u32 { | ||
| 402 | \\ return x; | ||
| 403 | \\} | ||
| 404 | \\ | ||
| 405 | \\fn assert(ok: bool) void { | ||
| 406 | \\ if (!ok) unreachable; | ||
| 407 | \\} | ||
| 408 | \\ | ||
| 409 | \\fn exit() noreturn { | ||
| 410 | \\ asm volatile ("svc #0" | ||
| 411 | \\ : | ||
| 412 | \\ : [number] "{r7}" (1), | ||
| 413 | \\ [arg1] "{r0}" (0) | ||
| 414 | \\ : "memory" | ||
| 415 | \\ ); | ||
| 416 | \\ unreachable; | ||
| 417 | \\} | ||
| 418 | , | ||
| 419 | "", | ||
| 420 | ); | ||
| 421 | } | ||
| 381 | } | 422 | } |