src/intrinsics/cpuid.rs

   1 //! Emulation of a subset of the cpuid x86 instruction.
   2
   3 use crate::prelude::*;
   4
   5 /// Emulates a subset of the cpuid x86 instruction.
   6 ///
   7 /// This emulates an intel cpu with sse and sse2 support, but which doesn't support anything else.
   8 pub(crate) fn codegen_cpuid_call<'tcx>(
   9     fx: &mut FunctionCx<'_, 'tcx, impl Module>,
  10     leaf: Value,
  11     _subleaf: Value,
  12 ) -> (Value, Value, Value, Value) {
  13     let leaf_0 = fx.bcx.create_block();
  14     let leaf_1 = fx.bcx.create_block();
  15     let leaf_8000_0000 = fx.bcx.create_block();
  16     let leaf_8000_0001 = fx.bcx.create_block();
  17     let unsupported_leaf = fx.bcx.create_block();
  18
  19     let dest = fx.bcx.create_block();
  20     let eax = fx.bcx.append_block_param(dest, types::I32);
  21     let ebx = fx.bcx.append_block_param(dest, types::I32);
  22     let ecx = fx.bcx.append_block_param(dest, types::I32);
  23     let edx = fx.bcx.append_block_param(dest, types::I32);
  24
  25     let mut switch = cranelift_frontend::Switch::new();
  26     switch.set_entry(0, leaf_0);
  27     switch.set_entry(1, leaf_1);
  28     switch.set_entry(0x8000_0000, leaf_8000_0000);
  29     switch.set_entry(0x8000_0001, leaf_8000_0001);
  30     switch.emit(&mut fx.bcx, leaf, unsupported_leaf);
  31
  32     fx.bcx.switch_to_block(leaf_0);
  33     let max_basic_leaf = fx.bcx.ins().iconst(types::I32, 1);
  34     let vend0 = fx
  35         .bcx
  36         .ins()
  37         .iconst(types::I32, i64::from(u32::from_le_bytes(*b"Genu")));
  38     let vend2 = fx
  39         .bcx
  40         .ins()
  41         .iconst(types::I32, i64::from(u32::from_le_bytes(*b"ineI")));
  42     let vend1 = fx
  43         .bcx
  44         .ins()
  45         .iconst(types::I32, i64::from(u32::from_le_bytes(*b"ntel")));
  46     fx.bcx
  47         .ins()
  48         .jump(dest, &[max_basic_leaf, vend0, vend1, vend2]);
  49
  50     fx.bcx.switch_to_block(leaf_1);
  51     let cpu_signature = fx.bcx.ins().iconst(types::I32, 0);
  52     let additional_information = fx.bcx.ins().iconst(types::I32, 0);
  53     let ecx_features = fx.bcx.ins().iconst(types::I32, 0);
  54     let edx_features = fx
  55         .bcx
  56         .ins()
  57         .iconst(types::I32, 1 << 25 /* sse */ | 1 << 26 /* sse2 */);
  58     fx.bcx.ins().jump(
  59         dest,
  60         &[
  61             cpu_signature,
  62             additional_information,
  63             ecx_features,
  64             edx_features,
  65         ],
  66     );
  67
  68     fx.bcx.switch_to_block(leaf_8000_0000);
  69     let extended_max_basic_leaf = fx.bcx.ins().iconst(types::I32, 0);
  70     let zero = fx.bcx.ins().iconst(types::I32, 0);
  71     fx.bcx
  72         .ins()
  73         .jump(dest, &[extended_max_basic_leaf, zero, zero, zero]);
  74
  75     fx.bcx.switch_to_block(leaf_8000_0001);
  76     let zero = fx.bcx.ins().iconst(types::I32, 0);
  77     let proc_info_ecx = fx.bcx.ins().iconst(types::I32, 0);
  78     let proc_info_edx = fx.bcx.ins().iconst(types::I32, 0);
  79     fx.bcx
  80         .ins()
  81         .jump(dest, &[zero, zero, proc_info_ecx, proc_info_edx]);
  82
  83     fx.bcx.switch_to_block(unsupported_leaf);
  84     crate::trap::trap_unreachable(
  85         fx,
  86         "__cpuid_count arch intrinsic doesn't yet support specified leaf",
  87     );
  88
  89     fx.bcx.switch_to_block(dest);
  90     fx.bcx.ins().nop();
  91
  92     (eax, ebx, ecx, edx)
  93 }