motiejus/zig
1
Fork 0
Code Releases Activity

Merge pull request #15639 from jacobly0/signed-mod

Browse Source 
llvm/cbe: fix signed `@mod`/`@divFloor` computations
This commit is contained in:
Andrew Kelley
2023-05-11 08:36:33 -07:00
committed by GitHub
parent c857959372 2e6a6d7564
commit 5569e6b49d
4 changed files with 65 additions and 49 deletions
Download Patch File Download Diff File Expand all files Collapse all files

13
src/codegen/c.zig
View File

@@ -6508,23 +6508,16 @@ fn airSplat(f: *Function, inst: Air.Inst.Index) !CValue {
const inst_ty = f.air.typeOfIndex(inst);
const inst_scalar_ty = inst_ty.scalarType();
const inst_scalar_cty = try f.typeToIndex(inst_scalar_ty, .complete);
const need_memcpy = f.indexToCType(inst_scalar_cty).tag() == .array;
const writer = f.object.writer();
const local = try f.allocLocal(inst, inst_ty);
const v = try Vectorize.start(f, inst, writer, inst_ty);
if (need_memcpy) try writer.writeAll("memcpy(&");
const a = try Assignment.init(f, inst_scalar_ty);
try f.writeCValue(writer, local, .Other);
try v.elem(f, writer);
try writer.writeAll(if (need_memcpy) ", &" else " = ");
try a.assign(f, writer);
try f.writeCValue(writer, operand, .Other);
if (need_memcpy) {
try writer.writeAll(", sizeof(");
try f.renderCType(writer, inst_scalar_cty);
try writer.writeAll("))");
}
try writer.writeAll(";\n");
try a.end(f, writer);
try v.end(f, inst, writer);
return local;

59
src/codegen/llvm.zig
View File

@@ -7215,20 +7215,28 @@ pub const FuncGen = struct {
return self.buildFloatOp(.floor, inst_ty, 1, .{result});
}
if (scalar_ty.isSignedInt()) {
// const d = @divTrunc(a, b);
// const r = @rem(a, b);
// return if (r == 0) d else d - ((a < 0) ^ (b < 0));
const result_llvm_ty = try self.dg.lowerType(inst_ty);
const zero = result_llvm_ty.constNull();
const div_trunc = self.builder.buildSDiv(lhs, rhs, "");
const target = self.dg.module.getTarget();
const inst_llvm_ty = try self.dg.lowerType(inst_ty);
const scalar_bit_size_minus_one = scalar_ty.bitSize(target) - 1;
const bit_size_minus_one = if (inst_ty.zigTypeTag() == .Vector) const_vector: {
const vec_len = inst_ty.vectorLen();
const scalar_llvm_ty = try self.dg.lowerType(scalar_ty);
const shifts = try self.gpa.alloc(*llvm.Value, vec_len);
defer self.gpa.free(shifts);
@memset(shifts, scalar_llvm_ty.constInt(scalar_bit_size_minus_one, .False));
break :const_vector llvm.constVector(shifts.ptr, vec_len);
} else inst_llvm_ty.constInt(scalar_bit_size_minus_one, .False);
const div = self.builder.buildSDiv(lhs, rhs, "");
const rem = self.builder.buildSRem(lhs, rhs, "");
const rem_eq_0 = self.builder.buildICmp(.EQ, rem, zero, "");
const a_lt_0 = self.builder.buildICmp(.SLT, lhs, zero, "");
const b_lt_0 = self.builder.buildICmp(.SLT, rhs, zero, "");
const a_b_xor = self.builder.buildXor(a_lt_0, b_lt_0, "");
const a_b_xor_ext = self.builder.buildZExt(a_b_xor, div_trunc.typeOf(), "");
const d_sub_xor = self.builder.buildSub(div_trunc, a_b_xor_ext, "");
return self.builder.buildSelect(rem_eq_0, div_trunc, d_sub_xor, "");
const div_sign = self.builder.buildXor(lhs, rhs, "");
const div_sign_mask = self.builder.buildAShr(div_sign, bit_size_minus_one, "");
const zero = inst_llvm_ty.constNull();
const rem_nonzero = self.builder.buildICmp(.NE, rem, zero, "");
const correction = self.builder.buildSelect(rem_nonzero, div_sign_mask, zero, "");
return self.builder.buildNSWAdd(div, correction, "");
}
return self.builder.buildUDiv(lhs, rhs, "");
}
@@ -7280,12 +7288,27 @@ pub const FuncGen = struct {
return self.builder.buildSelect(ltz, c, a, "");
}
if (scalar_ty.isSignedInt()) {
const a = self.builder.buildSRem(lhs, rhs, "");
const b = self.builder.buildNSWAdd(a, rhs, "");
const c = self.builder.buildSRem(b, rhs, "");
const target = self.dg.module.getTarget();
const scalar_bit_size_minus_one = scalar_ty.bitSize(target) - 1;
const bit_size_minus_one = if (inst_ty.zigTypeTag() == .Vector) const_vector: {
const vec_len = inst_ty.vectorLen();
const scalar_llvm_ty = try self.dg.lowerType(scalar_ty);
const shifts = try self.gpa.alloc(*llvm.Value, vec_len);
defer self.gpa.free(shifts);
@memset(shifts, scalar_llvm_ty.constInt(scalar_bit_size_minus_one, .False));
break :const_vector llvm.constVector(shifts.ptr, vec_len);
} else inst_llvm_ty.constInt(scalar_bit_size_minus_one, .False);
const rem = self.builder.buildSRem(lhs, rhs, "");
const div_sign = self.builder.buildXor(lhs, rhs, "");
const div_sign_mask = self.builder.buildAShr(div_sign, bit_size_minus_one, "");
const rhs_masked = self.builder.buildAnd(rhs, div_sign_mask, "");
const zero = inst_llvm_ty.constNull();
const ltz = self.builder.buildICmp(.SLT, lhs, zero, "");
return self.builder.buildSelect(ltz, c, a, "");
const rem_nonzero = self.builder.buildICmp(.NE, rem, zero, "");
const correction = self.builder.buildSelect(rem_nonzero, rhs_masked, zero, "");
return self.builder.buildNSWAdd(rem, correction, "");
}
return self.builder.buildURem(lhs, rhs, "");
}