From e106e18d96595bdc4bc037e0b36900992a576160 Mon Sep 17 00:00:00 2001
From: Robin Voetter <robin@voetter.nl>
Date: Tue, 21 Dec 2021 01:38:46 +0100
Subject: stage2: @shlWithOverflow

---
 src/codegen/c.zig    |  7 +++++++
 src/codegen/llvm.zig | 36 ++++++++++++++++++++++++++++++++++++
 2 files changed, 43 insertions(+)

(limited to 'src/codegen')

diff --git a/src/codegen/c.zig b/src/codegen/c.zig
index 68b700db17..12ce813a0f 100644
--- a/src/codegen/c.zig
+++ b/src/codegen/c.zig
@@ -1159,6 +1159,7 @@ fn genBody(f: *Function, body: []const Air.Inst.Index) error{ AnalysisFail, OutO
             .add_with_overflow => try airAddWithOverflow(f, inst),
             .sub_with_overflow => try airSubWithOverflow(f, inst),
             .mul_with_overflow => try airMulWithOverflow(f, inst),
+            .shl_with_overflow => try airShlWithOverflow(f, inst),
 
             .min => try airMinMax(f, inst, "<"),
             .max => try airMinMax(f, inst, ">"),
@@ -1887,6 +1888,12 @@ fn airMulWithOverflow(f: *Function, inst: Air.Inst.Index) !CValue {
     return f.fail("TODO mul with overflow", .{});
 }
 
+fn airShlWithOverflow(f: *Function, inst: Air.Inst.Index) !CValue {
+    _ = f;
+    _ = inst;
+    return f.fail("TODO shl with overflow", .{});
+}
+
 fn airNot(f: *Function, inst: Air.Inst.Index) !CValue {
     if (f.liveness.isUnused(inst))
         return CValue.none;
diff --git a/src/codegen/llvm.zig b/src/codegen/llvm.zig
index 4089a39cb3..78848bee28 100644
--- a/src/codegen/llvm.zig
+++ b/src/codegen/llvm.zig
@@ -1721,6 +1721,7 @@ pub const FuncGen = struct {
                 .add_with_overflow => try self.airOverflow(inst, "llvm.sadd.with.overflow", "llvm.uadd.with.overflow"),
                 .sub_with_overflow => try self.airOverflow(inst, "llvm.ssub.with.overflow", "llvm.usub.with.overflow"),
                 .mul_with_overflow => try self.airOverflow(inst, "llvm.smul.with.overflow", "llvm.umul.with.overflow"),
+                .shl_with_overflow => try self.airShlWithOverflow(inst),
 
                 .bit_and, .bool_and => try self.airAnd(inst),
                 .bit_or, .bool_or   => try self.airOr(inst),
@@ -3176,6 +3177,41 @@ pub const FuncGen = struct {
         return overflow_bit;
     }
 
+    fn airShlWithOverflow(self: *FuncGen, inst: Air.Inst.Index) !?*const llvm.Value {
+        if (self.liveness.isUnused(inst))
+            return null;
+
+        const pl_op = self.air.instructions.items(.data)[inst].pl_op;
+        const extra = self.air.extraData(Air.Bin, pl_op.payload).data;
+
+        const ptr = try self.resolveInst(pl_op.operand);
+        const lhs = try self.resolveInst(extra.lhs);
+        const rhs = try self.resolveInst(extra.rhs);
+
+        const ptr_ty = self.air.typeOf(pl_op.operand);
+        const lhs_ty = self.air.typeOf(extra.lhs);
+        const rhs_ty = self.air.typeOf(extra.rhs);
+
+        const tg = self.dg.module.getTarget();
+
+        const casted_rhs = if (rhs_ty.bitSize(tg) < lhs_ty.bitSize(tg))
+            self.builder.buildZExt(rhs, try self.dg.llvmType(lhs_ty), "")
+        else
+            rhs;
+
+        const result = self.builder.buildShl(lhs, casted_rhs, "");
+        const reconstructed = if (lhs_ty.isSignedInt())
+            self.builder.buildAShr(result, casted_rhs, "")
+        else
+            self.builder.buildLShr(result, casted_rhs, "");
+
+        const overflow_bit = self.builder.buildICmp(.NE, lhs, reconstructed, "");
+
+        self.store(ptr, ptr_ty, result, .NotAtomic);
+
+        return overflow_bit;
+    }
+
     fn airAnd(self: *FuncGen, inst: Air.Inst.Index) !?*const llvm.Value {
         if (self.liveness.isUnused(inst))
             return null;
-- 
cgit v1.2.3