Commit c9a153c7978b363a252f83878f75bd875fe6ae5e | zig

author	Jakub Konka <kubkon@jakubkonka.com> 2023-03-11 09:29:53+01:00
committer	Jakub Konka <kubkon@jakubkonka.com> 2023-03-11 20:05:50+01:00
log	c9a153c7978b363a252f83878f75bd875fe6ae5e
tree	fe460ceca16048242c35f94bd9bf0479c85f15a4
parent	621fc36b55a882c562d9378d4cf1fd8a5e1a907c

x86_64: add .dead pseudo-instruction to mark an unused MIR instruction

3 files changed, 14 insertions(+), 8 deletions(-)

src
- arch
  - x86_64
    CodeGen.zig
    Emit.zig
    Mir.zig

src/arch/x86_64/CodeGen.zig+8-8

...	@@ -630,8 +630,8 @@ fn gen(self: *Self) InnerError!void {	...	@@ -630,8 +630,8 @@ fn gen(self: *Self) InnerError!void {
630	// TODO During semantic analysis, check if there are no function calls. If there	630	// TODO During semantic analysis, check if there are no function calls. If there
631	// are none, here we can omit the part where we subtract and then add rsp.	631	// are none, here we can omit the part where we subtract and then add rsp.
632	const backpatch_stack_sub = try self.addInst(.{	632	const backpatch_stack_sub = try self.addInst(.{
633	.tag = .nop,	633	.tag = .dead,
634	.ops = .none,	634	.ops = undefined,
635	.data = undefined,	635	.data = undefined,
636	});	636	});
637		637
...	@@ -657,8 +657,8 @@ fn gen(self: *Self) InnerError!void {	...	@@ -657,8 +657,8 @@ fn gen(self: *Self) InnerError!void {
657		657
658	// Push callee-preserved regs that were used actually in use.	658	// Push callee-preserved regs that were used actually in use.
659	const backpatch_push_callee_preserved_regs = try self.addInst(.{	659	const backpatch_push_callee_preserved_regs = try self.addInst(.{
660	.tag = .nop,	660	.tag = .dead,
661	.ops = .none,	661	.ops = undefined,
662	.data = undefined,	662	.data = undefined,
663	});	663	});
664		664
...	@@ -688,8 +688,8 @@ fn gen(self: *Self) InnerError!void {	...	@@ -688,8 +688,8 @@ fn gen(self: *Self) InnerError!void {
688		688
689	// Pop saved callee-preserved regs.	689	// Pop saved callee-preserved regs.
690	const backpatch_pop_callee_preserved_regs = try self.addInst(.{	690	const backpatch_pop_callee_preserved_regs = try self.addInst(.{
691	.tag = .nop,	691	.tag = .dead,
692	.ops = .none,	692	.ops = undefined,
693	.data = undefined,	693	.data = undefined,
694	});	694	});
695		695
...	@@ -701,8 +701,8 @@ fn gen(self: *Self) InnerError!void {	...	@@ -701,8 +701,8 @@ fn gen(self: *Self) InnerError!void {
701		701
702	// Maybe add rsp, x if required. This is backpatched later.	702	// Maybe add rsp, x if required. This is backpatched later.
703	const backpatch_stack_add = try self.addInst(.{	703	const backpatch_stack_add = try self.addInst(.{
704	.tag = .nop,	704	.tag = .dead,
705	.ops = .none,	705	.ops = undefined,
706	.data = undefined,	706	.data = undefined,
707	});	707	});
708		708

src/arch/x86_64/Emit.zig+2

...	@@ -137,6 +137,8 @@ pub fn lowerMir(emit: *Emit) InnerError!void {	...	@@ -137,6 +137,8 @@ pub fn lowerMir(emit: *Emit) InnerError!void {
137		137
138	.push_regs => try emit.mirPushPopRegisterList(.push, inst),	138	.push_regs => try emit.mirPushPopRegisterList(.push, inst),
139	.pop_regs => try emit.mirPushPopRegisterList(.pop, inst),	139	.pop_regs => try emit.mirPushPopRegisterList(.pop, inst),
		140
		141	.dead => {},
140	}	142	}
141	}	143	}
142		144

src/arch/x86_64/Mir.zig+4

 @@ -163,6 +163,10 @@ pub const Inst = struct {
         /// Pop registers
         /// Uses `payload` payload with data of type `SaveRegisterList`.
         pop_regs,
+        /// Tombstone
+        /// Emitter should skip this instruction.
+        dead,
     };
     pub const Ops = enum(u8) {