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; RUN: llc -mtriple=x86_64-unknown-unknown -mcpu=x86-64 -mattr=avx -enable-unsafe-fp-math < %s | FileCheck %s
; Verify that the first two adds are independent regardless of how the inputs are
; commuted. The destination registers are used as source registers for the third add.
define float @reassociate_adds1(float %x0, float %x1, float %x2, float %x3) {
; CHECK-LABEL: reassociate_adds1:
; CHECK: # BB#0:
; CHECK-NEXT: vaddss %xmm1, %xmm0, %xmm0
; CHECK-NEXT: vaddss %xmm3, %xmm2, %xmm1
; CHECK-NEXT: vaddss %xmm1, %xmm0, %xmm0
; CHECK-NEXT: retq
%t0 = fadd float %x0, %x1
%t1 = fadd float %t0, %x2
%t2 = fadd float %t1, %x3
ret float %t2
}
define float @reassociate_adds2(float %x0, float %x1, float %x2, float %x3) {
; CHECK-LABEL: reassociate_adds2:
; CHECK: # BB#0:
; CHECK-NEXT: vaddss %xmm1, %xmm0, %xmm0
; CHECK-NEXT: vaddss %xmm3, %xmm2, %xmm1
; CHECK-NEXT: vaddss %xmm1, %xmm0, %xmm0
; CHECK-NEXT: retq
%t0 = fadd float %x0, %x1
%t1 = fadd float %x2, %t0
%t2 = fadd float %t1, %x3
ret float %t2
}
define float @reassociate_adds3(float %x0, float %x1, float %x2, float %x3) {
; CHECK-LABEL: reassociate_adds3:
; CHECK: # BB#0:
; CHECK-NEXT: vaddss %xmm1, %xmm0, %xmm0
; CHECK-NEXT: vaddss %xmm3, %xmm2, %xmm1
; CHECK-NEXT: vaddss %xmm1, %xmm0, %xmm0
; CHECK-NEXT: retq
%t0 = fadd float %x0, %x1
%t1 = fadd float %t0, %x2
%t2 = fadd float %x3, %t1
ret float %t2
}
define float @reassociate_adds4(float %x0, float %x1, float %x2, float %x3) {
; CHECK-LABEL: reassociate_adds4:
; CHECK: # BB#0:
; CHECK-NEXT: vaddss %xmm1, %xmm0, %xmm0
; CHECK-NEXT: vaddss %xmm3, %xmm2, %xmm1
; CHECK-NEXT: vaddss %xmm1, %xmm0, %xmm0
; CHECK-NEXT: retq
%t0 = fadd float %x0, %x1
%t1 = fadd float %x2, %t0
%t2 = fadd float %x3, %t1
ret float %t2
}
; Verify that we reassociate some of these ops. The optimal balanced tree of adds is not
; produced because that would cost more compile time.
define float @reassociate_adds5(float %x0, float %x1, float %x2, float %x3, float %x4, float %x5, float %x6, float %x7) {
; CHECK-LABEL: reassociate_adds5:
; CHECK: # BB#0:
; CHECK-NEXT: vaddss %xmm1, %xmm0, %xmm0
; CHECK-NEXT: vaddss %xmm3, %xmm2, %xmm1
; CHECK-NEXT: vaddss %xmm1, %xmm0, %xmm0
; CHECK-NEXT: vaddss %xmm5, %xmm4, %xmm1
; CHECK-NEXT: vaddss %xmm6, %xmm1, %xmm1
; CHECK-NEXT: vaddss %xmm1, %xmm0, %xmm0
; CHECK-NEXT: vaddss %xmm7, %xmm0, %xmm0
; CHECK-NEXT: retq
%t0 = fadd float %x0, %x1
%t1 = fadd float %t0, %x2
%t2 = fadd float %t1, %x3
%t3 = fadd float %t2, %x4
%t4 = fadd float %t3, %x5
%t5 = fadd float %t4, %x6
%t6 = fadd float %t5, %x7
ret float %t6
}
; Verify that we only need two associative operations to reassociate the operands.
; Also, we should reassociate such that the result of the high latency division
; is used by the final 'add' rather than reassociating the %x3 operand with the
; division. The latter reassociation would not improve anything.
define float @reassociate_adds6(float %x0, float %x1, float %x2, float %x3) {
; CHECK-LABEL: reassociate_adds6:
; CHECK: # BB#0:
; CHECK-NEXT: vdivss %xmm1, %xmm0, %xmm0
; CHECK-NEXT: vaddss %xmm3, %xmm2, %xmm1
; CHECK-NEXT: vaddss %xmm1, %xmm0, %xmm0
; CHECK-NEXT: retq
%t0 = fdiv float %x0, %x1
%t1 = fadd float %x2, %t0
%t2 = fadd float %x3, %t1
ret float %t2
}
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