tests_lit/assembler/x86/immediate_encodings.ll

; Tests various aspects of x86 immediate encoding. Some encodings are shorter.
; For example, the encoding is shorter for 8-bit immediates or when using EAX.
; This assumes that EAX is chosen as the first free register in O2 mode.

; RUN: %p2i --filetype=obj --disassemble -i %s --args -O2 | FileCheck %s

define internal i32 @testXor8Imm8(i32 %arg) {
entry:
  %arg_i8 = trunc i32 %arg to i8
  %result_i8 = xor i8 %arg_i8, 127
  %result = zext i8 %result_i8 to i32
  ret i32 %result
}
; CHECK-LABEL: testXor8Imm8
; CHECK: 34 7f   xor al

define internal i32 @testXor8Imm8Neg(i32 %arg) {
entry:
  %arg_i8 = trunc i32 %arg to i8
  %result_i8 = xor i8 %arg_i8, -128
  %result = zext i8 %result_i8 to i32
  ret i32 %result
}
; CHECK-LABEL: testXor8Imm8Neg
; CHECK: 34 80   xor al

define internal i32 @testXor8Imm8NotEAX(i32 %arg, i32 %arg2, i32 %arg3) {
entry:
  %arg_i8 = trunc i32 %arg to i8
  %arg2_i8 = trunc i32 %arg2 to i8
  %arg3_i8 = trunc i32 %arg3 to i8
  %x1 = xor i8 %arg_i8, 127
  %x2 = xor i8 %arg2_i8, 127
  %x3 = xor i8 %arg3_i8, 127
  %x4 = add i8 %x1, %x2
  %x5 = add i8 %x4, %x3
  %result = zext i8 %x5 to i32
  ret i32 %result
}
; CHECK-LABEL: testXor8Imm8NotEAX
; CHECK: 80 f{{[1-3]}} 7f xor {{[^a]}}l

define internal i32 @testXor16Imm8(i32 %arg) {
entry:
  %arg_i16 = trunc i32 %arg to i16
  %result_i16 = xor i16 %arg_i16, 127
  %result = zext i16 %result_i16 to i32
  ret i32 %result
}
; CHECK-LABEL: testXor16Imm8
; CHECK: 66 83 f0 7f  xor ax

define internal i32 @testXor16Imm8Neg(i32 %arg) {
entry:
  %arg_i16 = trunc i32 %arg to i16
  %result_i16 = xor i16 %arg_i16, -128
  %result = zext i16 %result_i16 to i32
  ret i32 %result
}
; CHECK-LABEL: testXor16Imm8Neg
; CHECK: 66 83 f0 80  xor ax

define internal i32 @testXor16Imm16Eax(i32 %arg) {
entry:
  %arg_i16 = trunc i32 %arg to i16
  %tmp = xor i16 %arg_i16, 1024
  %result_i16 = add i16 %tmp, 1
  %result = zext i16 %result_i16 to i32
  ret i32 %result
}
; CHECK-LABEL: testXor16Imm16Eax
; CHECK: 66 35 00 04  xor ax
; CHECK-NEXT: add ax,0x1

define internal i32 @testXor16Imm16NegEax(i32 %arg) {
entry:
  %arg_i16 = trunc i32 %arg to i16
  %tmp = xor i16 %arg_i16, -256
  %result_i16 = add i16 %tmp, 1
  %result = zext i16 %result_i16 to i32
  ret i32 %result
}
; CHECK-LABEL: testXor16Imm16NegEax
; CHECK: 66 35 00 ff  xor ax
; CHECK-NEXT: add ax,0x1

define internal i32 @testXor16Imm16NotEAX(i32 %arg_i32, i32 %arg2_i32, i32 %arg3_i32) {
entry:
  %arg = trunc i32 %arg_i32 to i16
  %arg2 = trunc i32 %arg2_i32 to i16
  %arg3 = trunc i32 %arg3_i32 to i16
  %x = xor i16 %arg, 32767
  %x2 = xor i16 %arg2, 32767
  %x3 = xor i16 %arg3, 32767
  %add1 = add i16 %x, %x2
  %add2 = add i16 %add1, %x3
  %result = zext i16 %add2 to i32
  ret i32 %result
}
; CHECK-LABEL: testXor16Imm16NotEAX
; CHECK: 66 81 f{{[1-3]}} ff 7f  xor {{[^a]}}x
; CHECK-NEXT: 66 81 f{{[1-3]}} ff 7f  xor {{[^a]}}x

define internal i32 @testXor32Imm8(i32 %arg) {
entry:
  %result = xor i32 %arg, 127
  ret i32 %result
}
; CHECK-LABEL: testXor32Imm8
; CHECK: 83 f0 7f   xor eax

define internal i32 @testXor32Imm8Neg(i32 %arg) {
entry:
  %result = xor i32 %arg, -128
  ret i32 %result
}
; CHECK-LABEL: testXor32Imm8Neg
; CHECK: 83 f0 80   xor eax

define internal i32 @testXor32Imm32Eax(i32 %arg) {
entry:
  %result = xor i32 %arg, 16777216
  ret i32 %result
}
; CHECK-LABEL: testXor32Imm32Eax
; CHECK: 35 00 00 00 01   xor eax

define internal i32 @testXor32Imm32NegEax(i32 %arg) {
entry:
  %result = xor i32 %arg, -256
  ret i32 %result
}
; CHECK-LABEL: testXor32Imm32NegEax
; CHECK: 35 00 ff ff ff   xor eax

define internal i32 @testXor32Imm32NotEAX(i32 %arg, i32 %arg2, i32 %arg3) {
entry:
  %x = xor i32 %arg, 32767
  %x2 = xor i32 %arg2, 32767
  %x3 = xor i32 %arg3, 32767
  %add1 = add i32 %x, %x2
  %add2 = add i32 %add1, %x3
  ret i32 %add2
}
; CHECK-LABEL: testXor32Imm32NotEAX
; CHECK: 81 f{{[1-3]}} ff 7f 00 00   xor e{{[^a]}}x,

; Should be similar for add, sub, etc., so sample a few.

define internal i32 @testAdd8Imm8(i32 %arg) {
entry:
  %arg_i8 = trunc i32 %arg to i8
  %result_i8 = add i8 %arg_i8, 126
  %result = zext i8 %result_i8 to i32
  ret i32 %result
}
; CHECK-LABEL: testAdd8Imm8
; CHECK: 04 7e   add al

define internal i32 @testSub8Imm8(i32 %arg) {
entry:
  %arg_i8 = trunc i32 %arg to i8
  %result_i8 = sub i8 %arg_i8, 125
  %result = zext i8 %result_i8 to i32
  ret i32 %result
}
; CHECK-LABEL: testSub8Imm8
; CHECK: 2c 7d  sub al

; imul has some shorter 8-bit immediate encodings.
; It also has a shorter encoding for eax, but we don't do that yet.

define internal i32 @testMul16Imm8(i32 %arg) {
entry:
  %arg_i16 = trunc i32 %arg to i16
  %tmp = mul i16 %arg_i16, 99
  %result_i16 = add i16 %tmp, 1
  %result = zext i16 %result_i16 to i32
  ret i32 %result
}
; CHECK-LABEL: testMul16Imm8
; CHECK: 66 6b c0 63  imul ax,ax
; CHECK-NEXT: add ax,0x1

define internal i32 @testMul16Imm8Neg(i32 %arg) {
entry:
  %arg_i16 = trunc i32 %arg to i16
  %tmp = mul i16 %arg_i16, -111
  %result_i16 = add i16 %tmp, 1
  %result = zext i16 %result_i16 to i32
  ret i32 %result
}
; CHECK-LABEL: testMul16Imm8Neg
; CHECK: 66 6b c0 91  imul ax,ax
; CHECK-NEXT: add ax,0x1

define internal i32 @testMul16Imm16(i32 %arg) {
entry:
  %arg_i16 = trunc i32 %arg to i16
  %tmp = mul i16 %arg_i16, 1025
  %result_i16 = add i16 %tmp, 1
  %result = zext i16 %result_i16 to i32
  ret i32 %result
}
; CHECK-LABEL: testMul16Imm16
; CHECK: 66 69 c0 01 04  imul ax,ax
; CHECK-NEXT: add ax,0x1

define internal i32 @testMul16Imm16Neg(i32 %arg) {
entry:
  %arg_i16 = trunc i32 %arg to i16
  %tmp = mul i16 %arg_i16, -255
  %result_i16 = add i16 %tmp, 1
  %result = zext i16 %result_i16 to i32
  ret i32 %result
}
; CHECK-LABEL: testMul16Imm16Neg
; CHECK: 66 69 c0 01 ff  imul ax,ax,0xff01
; CHECK-NEXT: add ax,0x1

define internal i32 @testMul32Imm8(i32 %arg) {
entry:
  %result = mul i32 %arg, 99
  ret i32 %result
}
; CHECK-LABEL: testMul32Imm8
; CHECK: 6b c0 63  imul eax,eax

define internal i32 @testMul32Imm8Neg(i32 %arg) {
entry:
  %result = mul i32 %arg, -111
  ret i32 %result
}
; CHECK-LABEL: testMul32Imm8Neg
; CHECK: 6b c0 91  imul eax,eax

define internal i32 @testMul32Imm16(i32 %arg) {
entry:
  %result = mul i32 %arg, 1025
  ret i32 %result
}
; CHECK-LABEL: testMul32Imm16
; CHECK: 69 c0 01 04 00 00  imul eax,eax

define internal i32 @testMul32Imm16Neg(i32 %arg) {
entry:
  %result = mul i32 %arg, -255
  ret i32 %result
}
; CHECK-LABEL: testMul32Imm16Neg
; CHECK: 69 c0 01 ff ff ff  imul eax,eax,0xffffff01

; The GPR shift instructions either allow an 8-bit immediate or
; have a special encoding for "1".
define internal i32 @testShl16Imm8(i32 %arg) {
entry:
  %arg_i16 = trunc i32 %arg to i16
  %tmp = shl i16 %arg_i16, 13
  %result = zext i16 %tmp to i32
  ret i32 %result
}
; CHECK-LABEL: testShl16Imm8
; CHECK: 66 c1 e0 0d shl ax,0xd

define internal i32 @testShl16Imm1(i32 %arg) {
entry:
  %arg_i16 = trunc i32 %arg to i16
  %tmp = shl i16 %arg_i16, 1
  %result = zext i16 %tmp to i32
  ret i32 %result
}
; CHECK-LABEL: testShl16Imm1
; CHECK: 66 d1 e0 shl ax

; Currently the "test" instruction is used for 64-bit shifts, and
; for ctlz 64-bit, so we use those to test the "test" instruction.
; One optimization for "test": the "test" instruction is essentially a
; bitwise AND that doesn't modify the two source operands, so for immediates
; under 8-bits and registers with 8-bit variants we can use the shorter form.

define internal i64 @test_via_shl64Bit(i64 %a, i64 %b) {
entry:
  %shl = shl i64 %a, %b
  ret i64 %shl
}
; CHECK-LABEL: test_via_shl64Bit
; CHECK: 0f a5 c2  shld edx,eax,cl
; CHECK: d3 e0     shl eax,cl
; CHECK: f6 c1 20  test cl,0x20

; Test a few register encodings of "test".
declare i64 @llvm.ctlz.i64(i64, i1)

define i64 @test_via_ctlz_64(i64 %x, i64 %y, i64 %z, i64 %w) {
entry:
  %r = call i64 @llvm.ctlz.i64(i64 %x, i1 false)
  %r2 = call i64 @llvm.ctlz.i64(i64 %y, i1 false)
  %r3 = call i64 @llvm.ctlz.i64(i64 %z, i1 false)
  %r4 = call i64 @llvm.ctlz.i64(i64 %w, i1 false)
  %res1 = add i64 %r, %r2
  %res2 = add i64 %r3, %r4
  %res = add i64 %res1, %res2
  ret i64 %res
}
; CHECK-LABEL: test_via_ctlz_64
; CHECK-DAG: 85 c0 test eax,eax
; CHECK-DAG: 85 db test ebx,ebx
; CHECK-DAG: 85 f6 test esi,esi