[InstCombine] improve perf by not creating a known non-canonical instruction
Op1 (RHS) is a constant, so putting it on the LHS makes us churn through visitICmp
an extra time to canonicalize it:
INSTCOMBINE ITERATION #1 on cmpnot
IC: ADDING: 3 instrs to worklist
IC: Visiting: %notx = xor i8 %x, -1
IC: Visiting: %cmp = icmp sgt i8 %notx, 42
IC: Old = %cmp = icmp sgt i8 %notx, 42
New = <badref> = icmp sgt i8 -43, %x
IC: ADD: %cmp = icmp sgt i8 -43, %x
IC: ERASE %1 = icmp sgt i8 %notx, 42
IC: ADD: %notx = xor i8 %x, -1
IC: DCE: %notx = xor i8 %x, -1
IC: ERASE %notx = xor i8 %x, -1
IC: Visiting: %cmp = icmp sgt i8 -43, %x
IC: Mod = %cmp = icmp sgt i8 -43, %x
New = %cmp = icmp slt i8 %x, -43
IC: ADD: %cmp = icmp slt i8 %x, -43
IC: Visiting: %cmp = icmp slt i8 %x, -43
IC: Visiting: ret i1 %cmp
If we create the swapped ICmp directly, we go faster:
INSTCOMBINE ITERATION #1 on cmpnot
IC: ADDING: 3 instrs to worklist
IC: Visiting: %notx = xor i8 %x, -1
IC: Visiting: %cmp = icmp sgt i8 %notx, 42
IC: Old = %cmp = icmp sgt i8 %notx, 42
New = <badref> = icmp slt i8 %x, -43
IC: ADD: %cmp = icmp slt i8 %x, -43
IC: ERASE %1 = icmp sgt i8 %notx, 42
IC: ADD: %notx = xor i8 %x, -1
IC: DCE: %notx = xor i8 %x, -1
IC: ERASE %notx = xor i8 %x, -1
IC: Visiting: %cmp = icmp slt i8 %x, -43
IC: Visiting: ret i1 %cmp
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@304558 91177308-0d34-0410-b5e6-96231b3b80d8
1 file changed