Owen Anderson 2de9f545aa Add intermediate subtract instructions to reassociation worklist.
We sometimes create intermediate subtract instructions during
reassociation.  Adding these to the worklist to revisit exposes many
additional reassociation opportunities.

Patch by Aditya Nandakumar.

llvm-svn: 253240
2015-11-16 18:07:30 +00:00

31 lines
875 B
LLVM

; RUN: opt < %s -reassociate -S | FileCheck %s
define i64 @multistep1(i64 %a, i64 %b, i64 %c) {
; Check that a*a*b+a*a*c is turned into a*(a*(b+c)).
; CHECK-LABEL: @multistep1(
%t0 = mul i64 %a, %b
%t1 = mul i64 %a, %t0 ; a*(a*b)
%t2 = mul i64 %a, %c
%t3 = mul i64 %a, %t2 ; a*(a*c)
%t4 = add i64 %t1, %t3
; CHECK-NEXT: [[TMP1:%tmp.*]] = add i64 %c, %b
; CHECK-NEXT: [[TMP2:%tmp.*]] = mul i64 %a, %a
; CHECK-NEXT: mul i64 [[TMP2]], [[TMP1]]
; CHECK-NEXT: ret
ret i64 %t4
}
define i64 @multistep2(i64 %a, i64 %b, i64 %c, i64 %d) {
; Check that a*b+a*c+d is turned into a*(b+c)+d.
; CHECK-LABEL: @multistep2(
%t0 = mul i64 %a, %b
%t1 = mul i64 %a, %c
%t2 = add i64 %t1, %d ; a*c+d
%t3 = add i64 %t0, %t2 ; a*b+(a*c+d)
; CHECK-NEXT: add i64 %c, %b
; CHECK-NEXT: mul i64 %tmp{{.*}}, %a
; CHECK-NEXT: add i64 %tmp{{.*}}, %d
; CHECK-NEXT: ret
ret i64 %t3
}