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Fix iconst.i8 0 miscompilation

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This commit is contained in:
bjorn3
2020-12-11 17:17:18 +01:00
committed by Benjamin Bouvier
parent 1d90c329b4
commit 8f7f8ee0b4
4 changed files with 14 additions and 14 deletions
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5
cranelift/codegen/meta/src/isa/x86/encodings.rs
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@@ -549,10 +549,13 @@ fn define_moves(e: &mut PerCpuModeEncodings, shared_defs: &SharedDefinitions, r:
} }
e.enc64(bconst.bind(B64), rec_pu_id_bool.opcodes(&MOV_IMM).rex()); e.enc64(bconst.bind(B64), rec_pu_id_bool.opcodes(&MOV_IMM).rex());
// You may expect that i8 encodings would use 0x30 (XORB) to indicate that encodings should be
// on 8-bit operands (f.ex "xor %al, %al"). Cranelift currently does not know when it can
// safely drop the 0x66 prefix, so we explicitly select a wider but permissible opcode.
let is_zero_int = InstructionPredicate::new_is_zero_int(&formats.unary_imm, "imm"); let is_zero_int = InstructionPredicate::new_is_zero_int(&formats.unary_imm, "imm");
e.enc_both_instp( e.enc_both_instp(
iconst.bind(I8), iconst.bind(I8),
rec_u_id_z.opcodes(&XORB), rec_u_id_z.opcodes(&XOR),
is_zero_int.clone(), is_zero_int.clone(),
); );

3
cranelift/codegen/meta/src/isa/x86/opcodes.rs
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@@ -711,9 +711,6 @@ pub static XOR_IMM8_SIGN_EXTEND: [u8; 1] = [0x83];
/// r/m{16,32,64} XOR register of the same size. /// r/m{16,32,64} XOR register of the same size.
pub static XOR: [u8; 1] = [0x31]; pub static XOR: [u8; 1] = [0x31];
/// r/m8 XOR r8.
pub static XORB: [u8; 1] = [0x30];
/// Bitwise logical XOR of packed double-precision floating-point values. /// Bitwise logical XOR of packed double-precision floating-point values.
pub static XORPD: [u8; 3] = [0x66, 0x0f, 0x57]; pub static XORPD: [u8; 3] = [0x66, 0x0f, 0x57];

8
cranelift/filetests/filetests/isa/x86/optimized-zero-constants-32bit.clif
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@@ -44,9 +44,9 @@ block0:
function %zero_byte() -> i8 fast { function %zero_byte() -> i8 fast {
block0: block0:
; asm: xor %al, %al ; asm: xor %eax, %eax
[-,%rax] v0 = iconst.i8 0 ; bin: 30 c0 [-,%rax] v0 = iconst.i8 0 ; bin: 31 c0
; asm: xor %dh, %dh ; asm: xor %edi, %edi
[-,%rdi] v1 = iconst.i8 0 ; bin: 30 ff [-,%rdi] v1 = iconst.i8 0 ; bin: 31 ff
return v0 return v0
} }

12
cranelift/filetests/filetests/isa/x86/optimized-zero-constants.clif
View File

@@ -62,11 +62,11 @@ block0:
function %zero_byte() -> i8 fast { function %zero_byte() -> i8 fast {
block0: block0:
; asm: xor %r8b, %r8b ; asm: xor %r8d, %r8d
[-,%r15] v0 = iconst.i8 0 ; bin: 45 30 ff [-,%r15] v0 = iconst.i8 0 ; bin: 45 31 ff
; asm: xor %al, %al ; asm: xor %eax, eax
[-,%rax] v1 = iconst.i8 0 ; bin: 30 c0 [-,%rax] v1 = iconst.i8 0 ; bin: 31 c0
; asm: xor %dh, %dh ; asm: xor %edi, %edi
[-,%rdi] v2 = iconst.i8 0 ; bin: 30 ff [-,%rdi] v2 = iconst.i8 0 ; bin: 31 ff
return v0 return v0
} }