[X86] New test case for reassociation of ADD instructions.

[Carrot]

Summary

This is a pre-commit test case for D136396.

[pengfei]

LGTM.

[RKSimon]

LGTM - cheers

llvm/test/CodeGen/X86/reassociate-add.ll

10

something more descriptive than foo might be useful in case we ever add further tests to this file

[Carrot]

Thanks for the review. Will commit this version.

llvm/test/CodeGen/X86/reassociate-add.ll

+; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py
+; RUN: llc -mtriple=x86_64-unknown-unknown -mcpu=x86-64 < %s | FileCheck %s
+
+; This file checks the reassociation of ADD instruction.
+; The two ADD instructions add v0,v1,t2 together. t2 has a long dependence
+; chain, v0 and v1 has a short dependence chain, in order to get the shortest
+; latency, v0 and v1 should be added first, and its result is added to t2
+; later.
+
+define void @foo8(i8 %x0, i8 %x1, i8 %x2, i8* %p) {
+; CHECK-LABEL: foo8:
+; CHECK:       # %bb.0:
+; CHECK-NEXT:    orb $16, %dil
+; CHECK-NEXT:    orb $32, %sil
+; CHECK-NEXT:    addb $-8, %dl
+; CHECK-NEXT:    orb $7, %dl
+; CHECK-NEXT:    movzbl %dl, %eax
+; CHECK-NEXT:    imull $100, %eax, %eax
+; CHECK-NEXT:    addb %sil, %al
+; CHECK-NEXT:    addb %dil, %al
+; CHECK-NEXT:    movb %al, (%rcx)
+; CHECK-NEXT:    retq
+  %v0 = or i8 %x0, 16
+  %v1 = or i8 %x1, 32
+  %t0 = sub i8 %x2, 8
+  %t1 = or i8 %t0, 7
+  %t2 = mul i8 %t1, 100
+  %t3 = add i8 %t2, %v1
+  %t4 = add i8 %t3, %v0
+  store i8 %t4, i8* %p, align 4
+  ret void
+}
+
+define void @foo16(i16 %x0, i16 %x1, i16 %x2, i16* %p) {
+; CHECK-LABEL: foo16:
+; CHECK:       # %bb.0:
+; CHECK-NEXT:    orl $16, %edi
+; CHECK-NEXT:    orl $32, %esi
+; CHECK-NEXT:    addl $-8, %edx
+; CHECK-NEXT:    orl $7, %edx
+; CHECK-NEXT:    imull $100, %edx, %eax
+; CHECK-NEXT:    addl %esi, %eax
+; CHECK-NEXT:    addl %edi, %eax
+; CHECK-NEXT:    movw %ax, (%rcx)
+; CHECK-NEXT:    retq
+  %v0 = or i16 %x0, 16
+  %v1 = or i16 %x1, 32
+  %t0 = sub i16 %x2, 8
+  %t1 = or i16 %t0, 7
+  %t2 = mul i16 %t1, 100
+  %t3 = add i16 %t2, %v1
+  %t4 = add i16 %t3, %v0
+  store i16 %t4, i16* %p, align 4
+  ret void
+}
+
+define void @foo32(i32 %x0, i32 %x1, i32 %x2, i32* %p) {
+; CHECK-LABEL: foo32:
+; CHECK:       # %bb.0:
+; CHECK-NEXT:    orl $16, %edi
+; CHECK-NEXT:    orl $32, %esi
+; CHECK-NEXT:    addl $-8, %edx
+; CHECK-NEXT:    orl $7, %edx
+; CHECK-NEXT:    imull $100, %edx, %eax
+; CHECK-NEXT:    addl %esi, %eax
+; CHECK-NEXT:    addl %edi, %eax
+; CHECK-NEXT:    movl %eax, (%rcx)
+; CHECK-NEXT:    retq
+  %v0 = or i32 %x0, 16
+  %v1 = or i32 %x1, 32
+  %t0 = sub i32 %x2, 8
+  %t1 = or i32 %t0, 7
+  %t2 = mul i32 %t1, 100
+  %t3 = add i32 %t2, %v1
+  %t4 = add i32 %t3, %v0
+  store i32 %t4, i32* %p, align 4
+  ret void
+}
+
+define void @foo64(i64 %x0, i64 %x1, i64 %x2, i64* %p) {
+; CHECK-LABEL: foo64:
+; CHECK:       # %bb.0:
+; CHECK-NEXT:    orq $16, %rdi
+; CHECK-NEXT:    orq $32, %rsi
+; CHECK-NEXT:    addq $-8, %rdx
+; CHECK-NEXT:    orq $7, %rdx
+; CHECK-NEXT:    imulq $100, %rdx, %rax
+; CHECK-NEXT:    addq %rsi, %rax
+; CHECK-NEXT:    addq %rdi, %rax
+; CHECK-NEXT:    movq %rax, (%rcx)
+; CHECK-NEXT:    retq
+  %v0 = or i64 %x0, 16
+  %v1 = or i64 %x1, 32
+  %t0 = sub i64 %x2, 8
+  %t1 = or i64 %t0, 7
+  %t2 = mul i64 %t1, 100
+  %t3 = add i64 %t2, %v1
+  %t4 = add i64 %t3, %v0
+  store i64 %t4, i64* %p, align 4
+  ret void
+}
+
+; Negative test. Original sequence has shorter latency, don't transform it.
+define void @foo64_negative(i64 %x0, i64 %x1, i64 %x2, i64* %p) {
+; CHECK-LABEL: foo64_negative:
+; CHECK:       # %bb.0:
+; CHECK-NEXT:    orq $16, %rdi
+; CHECK-NEXT:    orq $32, %rsi
+; CHECK-NEXT:    addq %rdi, %rsi
+; CHECK-NEXT:    addq $-8, %rdx
+; CHECK-NEXT:    orq $7, %rdx
+; CHECK-NEXT:    imulq $100, %rdx, %rax
+; CHECK-NEXT:    addq %rsi, %rax
+; CHECK-NEXT:    movq %rax, (%rcx)
+; CHECK-NEXT:    retq
+  %v0 = or i64 %x0, 16
+  %v1 = or i64 %x1, 32
+  %t0 = sub i64 %x2, 8
+  %t1 = or i64 %t0, 7
+  %t2 = mul i64 %t1, 100
+  %t3 = add i64 %v0, %v1
+  %t4 = add i64 %t3, %t2
+  store i64 %t4, i64* %p, align 4
+  ret void
+}