Commit 4aae0b09cfdc444a0b4e98d3ed7f83bfe421c06f | zig

author	Andrew Kelley <andrew@ziglang.org> 2022-12-03 19:30:08-07:00
committer	Andrew Kelley <andrew@ziglang.org> 2022-12-04 15:57:40-07:00
log	4aae0b09cfdc444a0b4e98d3ed7f83bfe421c06f
tree	b39b9beb40acde354abd178a47f10a0f73d8af33
parent	f2e59e41c1ea3884a50e45f54a74c29f52954b24

CBE and LLVM: handle unused try instructions

In both backends they did not observe the Liveness information for try
instructions. Now they do. For the C backend this is necessary for
correctness; for the LLVM backend, it improves code generation.

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

src
- codegen
  - c.zig
  - llvm.zig

src/codegen/c.zig+6-1

 @@ -4092,9 +4092,14 @@ fn lowerTry(
         }
     }
+    try reap(f, inst, &.{operand});
+    if (f.liveness.isUnused(inst)) {
+        return CValue.none;
+    }
     const target = f.object.dg.module.getTarget();
     const is_array = lowersToArray(payload_ty, target);
-    try reap(f, inst, &.{operand});
     const local = try f.allocLocal(inst, result_ty);
     if (is_array) {
         try writer.writeAll("memcpy(");

src/codegen/llvm.zig+8-2

...	@@ -5346,7 +5346,8 @@ pub const FuncGen = struct {	...	@@ -5346,7 +5346,8 @@ pub const FuncGen = struct {
5346	const err_union_ty = self.air.typeOf(pl_op.operand);	5346	const err_union_ty = self.air.typeOf(pl_op.operand);
5347	const payload_ty = self.air.typeOfIndex(inst);	5347	const payload_ty = self.air.typeOfIndex(inst);
5348	const can_elide_load = if (isByRef(payload_ty)) self.canElideLoad(body_tail) else false;	5348	const can_elide_load = if (isByRef(payload_ty)) self.canElideLoad(body_tail) else false;
5349	return lowerTry(self, err_union, body, err_union_ty, false, can_elide_load, payload_ty);	5349	const is_unused = self.liveness.isUnused(inst);
		5350	return lowerTry(self, err_union, body, err_union_ty, false, can_elide_load, is_unused, payload_ty);
5350	}	5351	}
5351		5352
5352	fn airTryPtr(self: FuncGen, inst: Air.Inst.Index) !?llvm.Value {	5353	fn airTryPtr(self: FuncGen, inst: Air.Inst.Index) !?llvm.Value {
...	@@ -5356,7 +5357,8 @@ pub const FuncGen = struct {	...	@@ -5356,7 +5357,8 @@ pub const FuncGen = struct {
5356	const body = self.air.extra[extra.end..][0..extra.data.body_len];	5357	const body = self.air.extra[extra.end..][0..extra.data.body_len];
5357	const err_union_ty = self.air.typeOf(extra.data.ptr).childType();	5358	const err_union_ty = self.air.typeOf(extra.data.ptr).childType();
5358	const payload_ty = self.air.typeOfIndex(inst);	5359	const payload_ty = self.air.typeOfIndex(inst);
5359	return lowerTry(self, err_union_ptr, body, err_union_ty, true, true, payload_ty);	5360	const is_unused = self.liveness.isUnused(inst);
		5361	return lowerTry(self, err_union_ptr, body, err_union_ty, true, true, is_unused, payload_ty);
5360	}	5362	}
5361		5363
5362	fn lowerTry(	5364	fn lowerTry(
...	@@ -5366,6 +5368,7 @@ pub const FuncGen = struct {	...	@@ -5366,6 +5368,7 @@ pub const FuncGen = struct {
5366	err_union_ty: Type,	5368	err_union_ty: Type,
5367	operand_is_ptr: bool,	5369	operand_is_ptr: bool,
5368	can_elide_load: bool,	5370	can_elide_load: bool,
		5371	is_unused: bool,
5369	result_ty: Type,	5372	result_ty: Type,
5370	) !?*llvm.Value {	5373	) !?*llvm.Value {
5371	const payload_ty = err_union_ty.errorUnionPayload();	5374	const payload_ty = err_union_ty.errorUnionPayload();
...	@@ -5405,6 +5408,9 @@ pub const FuncGen = struct {	...	@@ -5405,6 +5408,9 @@ pub const FuncGen = struct {
5405		5408
5406	fg.builder.positionBuilderAtEnd(continue_block);	5409	fg.builder.positionBuilderAtEnd(continue_block);
5407	}	5410	}
		5411	if (is_unused) {
		5412	return null;
		5413	}
5408	if (!payload_has_bits) {	5414	if (!payload_has_bits) {
5409	if (!operand_is_ptr) return null;	5415	if (!operand_is_ptr) return null;
5410		5416