[llvm] r305985 - [InstCombine] Add test cases to demonstrate that and->xnor and or->xnor folding can create more instructions than it removed when there are multiple uses. NFC

[Craig Topper via llvm-commits]

Author: ctopper
Date: Thu Jun 22 00:20:39 2017
New Revision: 305985

URL: http://llvm.org/viewvc/llvm-project?rev=305985&view=rev
Log:
[InstCombine] Add test cases to demonstrate that and->xnor and or->xnor folding can create more instructions than it removed when there are multiple uses. NFC

Modified:
    llvm/trunk/test/Transforms/InstCombine/and-or-not.ll

Modified: llvm/trunk/test/Transforms/InstCombine/and-or-not.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/InstCombine/and-or-not.ll?rev=305985&r1=305984&r2=305985&view=diff
==============================================================================
--- llvm/trunk/test/Transforms/InstCombine/and-or-not.ll (original)
+++ llvm/trunk/test/Transforms/InstCombine/and-or-not.ll Thu Jun 22 00:20:39 2017
@@ -1,3 +1,4 @@
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
 ; RUN: opt < %s -instcombine -S | FileCheck %s
 
 ; PR1510
@@ -516,3 +517,52 @@ define i64 @PR32830(i64 %a, i64 %b, i64
   ret i64 %and
 }
 
+; (~a | b) & (~b | a) --> ~(a ^ b)
+; TODO: this increases instrunction count if the pieces have additional users
+define i32 @and_to_nxor_multiuse(float %fa, float %fb) {
+; CHECK-LABEL: @and_to_nxor_multiuse(
+; CHECK-NEXT:    [[A:%.*]] = fptosi float [[FA:%.*]] to i32
+; CHECK-NEXT:    [[B:%.*]] = fptosi float [[FB:%.*]] to i32
+; CHECK-NEXT:    [[NOTA:%.*]] = xor i32 [[A]], -1
+; CHECK-NEXT:    [[NOTB:%.*]] = xor i32 [[B]], -1
+; CHECK-NEXT:    [[OR1:%.*]] = or i32 [[NOTA]], [[B]]
+; CHECK-NEXT:    [[OR2:%.*]] = or i32 [[NOTB]], [[A]]
+; CHECK-NEXT:    [[TMP1:%.*]] = xor i32 [[B]], [[A]]
+; CHECK-NEXT:    [[AND:%.*]] = xor i32 [[TMP1]], -1
+; CHECK-NEXT:    [[MUL1:%.*]] = mul i32 [[OR1]], [[OR2]]
+; CHECK-NEXT:    [[MUL2:%.*]] = mul i32 [[MUL1]], [[AND]]
+; CHECK-NEXT:    ret i32 [[MUL2]]
+;
+  %a = fptosi float %fa to i32
+  %b = fptosi float %fb to i32
+  %nota = xor i32 %a, -1
+  %notb = xor i32 %b, -1
+  %or1 = or i32 %nota, %b
+  %or2 = or i32 %notb, %a
+  %and = and i32 %or1, %or2
+  %mul1 = mul i32 %or1, %or2 ; here to increase the use count of the inputs to the and
+  %mul2 = mul i32 %mul1, %and
+  ret i32 %mul2
+}
+
+; (a & b) | ~(a | b) --> ~(a ^ b)
+; TODO: this increases instrunction count if the pieces have additional users
+define i32 @or_to_nxor_multiuse(i32 %a, i32 %b) {
+; CHECK-LABEL: @or_to_nxor_multiuse(
+; CHECK-NEXT:    [[AND:%.*]] = and i32 [[A:%.*]], [[B:%.*]]
+; CHECK-NEXT:    [[OR:%.*]] = or i32 [[A]], [[B]]
+; CHECK-NEXT:    [[NOTOR:%.*]] = xor i32 [[OR]], -1
+; CHECK-NEXT:    [[TMP1:%.*]] = xor i32 [[A]], [[B]]
+; CHECK-NEXT:    [[OR2:%.*]] = xor i32 [[TMP1]], -1
+; CHECK-NEXT:    [[MUL1:%.*]] = mul i32 [[AND]], [[NOTOR]]
+; CHECK-NEXT:    [[MUL2:%.*]] = mul i32 [[MUL1]], [[OR2]]
+; CHECK-NEXT:    ret i32 [[MUL2]]
+;
+  %and = and i32 %a, %b
+  %or = or i32 %a, %b
+  %notor = xor i32 %or, -1
+  %or2 = or i32 %and, %notor
+  %mul1 = mul i32 %and, %notor ; here to increase the use count of the inputs to the or
+  %mul2 = mul i32 %mul1, %or2
+  ret i32 %mul2
+}