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stage2: LLVM backend: implement switch_br

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This commit is contained in:
Andrew Kelley
2021-10-20 14:10:37 -07:00
parent dfb3231959
commit ed2a5081e1
4 changed files with 268 additions and 235 deletions
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56
src/codegen/llvm.zig
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@@ -1993,23 +1993,55 @@ pub const FuncGen = struct {
const then_block = self.context.appendBasicBlock(self.llvm_func, "Then");
const else_block = self.context.appendBasicBlock(self.llvm_func, "Else");
{
const prev_block = self.builder.getInsertBlock();
defer self.builder.positionBuilderAtEnd(prev_block);
self.builder.positionBuilderAtEnd(then_block);
try self.genBody(then_body);
self.builder.positionBuilderAtEnd(else_block);
try self.genBody(else_body);
}
_ = self.builder.buildCondBr(cond, then_block, else_block);
self.builder.positionBuilderAtEnd(then_block);
try self.genBody(then_body);
self.builder.positionBuilderAtEnd(else_block);
try self.genBody(else_body);
// No need to reset the insert cursor since this instruction is noreturn.
return null;
}
fn airSwitchBr(self: *FuncGen, inst: Air.Inst.Index) !?*const llvm.Value {
_ = inst;
return self.todo("implement llvm codegen for switch_br", .{});
const pl_op = self.air.instructions.items(.data)[inst].pl_op;
const cond = try self.resolveInst(pl_op.operand);
const switch_br = self.air.extraData(Air.SwitchBr, pl_op.payload);
const else_block = self.context.appendBasicBlock(self.llvm_func, "Else");
const llvm_switch = self.builder.buildSwitch(cond, else_block, switch_br.data.cases_len);
var extra_index: usize = switch_br.end;
var case_i: u32 = 0;
while (case_i < switch_br.data.cases_len) : (case_i += 1) {
const case = self.air.extraData(Air.SwitchBr.Case, extra_index);
const items = @bitCast([]const Air.Inst.Ref, self.air.extra[case.end..][0..case.data.items_len]);
const case_body = self.air.extra[case.end + items.len ..][0..case.data.body_len];
extra_index = case.end + case.data.items_len + case_body.len;
const case_block = self.context.appendBasicBlock(self.llvm_func, "Case");
for (items) |item| {
const llvm_item = try self.resolveInst(item);
llvm_switch.addCase(llvm_item, case_block);
}
self.builder.positionBuilderAtEnd(case_block);
try self.genBody(case_body);
}
self.builder.positionBuilderAtEnd(else_block);
const else_body = self.air.extra[extra_index..][0..switch_br.data.else_body_len];
if (else_body.len != 0) {
try self.genBody(else_body);
} else {
_ = self.builder.buildUnreachable();
}
// No need to reset the insert cursor since this instruction is noreturn.
return null;
}
fn airLoop(self: *FuncGen, inst: Air.Inst.Index) !?*const llvm.Value {

6
src/codegen/llvm/bindings.zig
View File

@@ -178,6 +178,9 @@ pub const Value = opaque {
pub const setInitializer = LLVMSetInitializer;
extern fn LLVMSetInitializer(GlobalVar: *const Value, ConstantVal: *const Value) void;
pub const addCase = LLVMAddCase;
extern fn LLVMAddCase(Switch: *const Value, OnVal: *const Value, Dest: *const BasicBlock) void;
};
pub const Type = opaque {
@@ -554,6 +557,9 @@ pub const Builder = opaque {
pub const buildCondBr = LLVMBuildCondBr;
extern fn LLVMBuildCondBr(*const Builder, If: *const Value, Then: *const BasicBlock, Else: *const BasicBlock) *const Value;
pub const buildSwitch = LLVMBuildSwitch;
extern fn LLVMBuildSwitch(*const Builder, V: *const Value, Else: *const BasicBlock, NumCases: c_uint) *const Value;
pub const buildPhi = LLVMBuildPhi;
extern fn LLVMBuildPhi(*const Builder, Ty: *const Type, Name: [*:0]const u8) *const Value;