@bitreverse intrinsic, part of #767 (#1865)

* bitreverse - give bswap behavior

* bitreverse, comptime_ints, negative values still not working?

* bitreverse working for negative comptime ints

* Finished bitreverse test cases

* Undo exporting a bigint function. @bitreverse test name includes ampersand

* added docs entry for @bitreverse

1 files changed, 16 insertions, 0 deletions

diff --git a/src/codegen.cpp b/src/codegen.cpp
index 6a0596f62f..db8a5f7bb2 100644
--- a/src/codegen.cpp
+++ b/src/codegen.cpp
@@ -3789,6 +3789,11 @@ static LLVMValueRef get_int_builtin_fn(CodeGen *g, ZigType *int_type, BuiltinFnI
         n_args = 1;
         key.id = ZigLLVMFnIdBswap;
         key.data.bswap.bit_count = (uint32_t)int_type->data.integral.bit_count;
+    } else if (fn_id == BuiltinFnIdBitReverse) {
+        fn_name = "bitreverse";
+        n_args = 1;
+        key.id = ZigLLVMFnIdBitReverse;
+        key.data.bit_reverse.bit_count = (uint32_t)int_type->data.integral.bit_count;
     } else {
         zig_unreachable();
     }
@@ -5096,6 +5101,14 @@ static LLVMValueRef ir_render_bswap(CodeGen *g, IrExecutable *executable, IrInst
     return LLVMBuildTrunc(g->builder, shifted, int_type->type_ref, "");
 }
 
+static LLVMValueRef ir_render_bit_reverse(CodeGen *g, IrExecutable *executable, IrInstructionBitReverse *instruction) {
+    LLVMValueRef op = ir_llvm_value(g, instruction->op);
+    ZigType *int_type = instruction->base.value.type;
+    assert(int_type->id == ZigTypeIdInt);
+    LLVMValueRef fn_val = get_int_builtin_fn(g, instruction->base.value.type, BuiltinFnIdBitReverse);
+    return LLVMBuildCall(g->builder, fn_val, &op, 1, "");
+}
+
 static void set_debug_location(CodeGen *g, IrInstruction *instruction) {
     AstNode *source_node = instruction->source_node;
     Scope *scope = instruction->scope;
@@ -5335,6 +5348,8 @@ static LLVMValueRef ir_render_instruction(CodeGen *g, IrExecutable *executable,
             return ir_render_sqrt(g, executable, (IrInstructionSqrt *)instruction);
         case IrInstructionIdBswap:
             return ir_render_bswap(g, executable, (IrInstructionBswap *)instruction);
+        case IrInstructionIdBitReverse:
+            return ir_render_bit_reverse(g, executable, (IrInstructionBitReverse *)instruction);
     }
     zig_unreachable();
 }
@@ -6758,6 +6773,7 @@ static void define_builtin_fns(CodeGen *g) {
     create_builtin_fn(g, BuiltinFnIdFromBytes, "bytesToSlice", 2);
     create_builtin_fn(g, BuiltinFnIdThis, "This", 0);
     create_builtin_fn(g, BuiltinFnIdBswap, "bswap", 2);
+    create_builtin_fn(g, BuiltinFnIdBitReverse, "bitreverse", 2);
 }
 
 static const char *bool_to_str(bool b) {