[llvm] r329010 - [InstCombine] add tests for icmp (sub x, y), x (PR36969); NFC

[Sanjay Patel via llvm-commits]

Author: spatel
Date: Mon Apr  2 13:23:54 2018
New Revision: 329010

URL: http://llvm.org/viewvc/llvm-project?rev=329010&view=rev
Log:
[InstCombine] add tests for icmp (sub x, y), x (PR36969); NFC

Modified:
    llvm/trunk/test/Transforms/InstCombine/icmp.ll

Modified: llvm/trunk/test/Transforms/InstCombine/icmp.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/InstCombine/icmp.ll?rev=329010&r1=329009&r2=329010&view=diff
==============================================================================
--- llvm/trunk/test/Transforms/InstCombine/icmp.ll (original)
+++ llvm/trunk/test/Transforms/InstCombine/icmp.ll Mon Apr  2 13:23:54 2018
@@ -545,6 +545,36 @@ define i1 @test36(i32 %x, i32 %y) {
   ret i1 %c
 }
 
+; PR36969 - https://bugs.llvm.org/show_bug.cgi?id=36969
+
+define i1 @ugt_sub(i32 %xsrc, i32 %y) {
+; CHECK-LABEL: @ugt_sub(
+; CHECK-NEXT:    [[X:%.*]] = udiv i32 [[XSRC:%.*]], 42
+; CHECK-NEXT:    [[SUB:%.*]] = sub i32 [[X]], [[Y:%.*]]
+; CHECK-NEXT:    [[CMP:%.*]] = icmp ugt i32 [[SUB]], [[X]]
+; CHECK-NEXT:    ret i1 [[CMP]]
+;
+  %x = udiv i32 %xsrc, 42 ; thwart complexity-based canonicalization
+  %sub = sub i32 %x, %y
+  %cmp = icmp ugt i32 %sub, %x
+  ret i1 %cmp
+}
+
+; Swap operands and predicate. Try a vector type to verify that works too.
+
+define <2 x i1> @ult_sub(<2 x i8> %xsrc, <2 x i8> %y) {
+; CHECK-LABEL: @ult_sub(
+; CHECK-NEXT:    [[X:%.*]] = udiv <2 x i8> [[XSRC:%.*]], <i8 42, i8 -42>
+; CHECK-NEXT:    [[SUB:%.*]] = sub <2 x i8> [[X]], [[Y:%.*]]
+; CHECK-NEXT:    [[CMP:%.*]] = icmp ult <2 x i8> [[X]], [[SUB]]
+; CHECK-NEXT:    ret <2 x i1> [[CMP]]
+;
+  %x = udiv <2 x i8> %xsrc, <i8 42, i8 -42> ; thwart complexity-based canonicalization
+  %sub = sub <2 x i8> %x, %y
+  %cmp = icmp ult <2 x i8> %x, %sub
+  ret <2 x i1> %cmp
+}
+
 ; X - Y > X - Z -> Z > Y if there is no overflow.
 define i1 @test37(i32 %x, i32 %y, i32 %z) {
 ; CHECK-LABEL: @test37(