[llvm] r294524 - [InstCombine] add tests to show information-losing add nsw/nuw transforms; NFC
Sanjay Patel via llvm-commits
llvm-commits at lists.llvm.org
Wed Feb 8 14:14:11 PST 2017
Author: spatel
Date: Wed Feb 8 16:14:11 2017
New Revision: 294524
URL: http://llvm.org/viewvc/llvm-project?rev=294524&view=rev
Log:
[InstCombine] add tests to show information-losing add nsw/nuw transforms; NFC
Modified:
llvm/trunk/test/Transforms/InstCombine/add.ll
llvm/trunk/test/Transforms/InstCombine/icmp-add.ll
llvm/trunk/test/Transforms/InstCombine/sub-xor.ll
Modified: llvm/trunk/test/Transforms/InstCombine/add.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/InstCombine/add.ll?rev=294524&r1=294523&r2=294524&view=diff
==============================================================================
--- llvm/trunk/test/Transforms/InstCombine/add.ll (original)
+++ llvm/trunk/test/Transforms/InstCombine/add.ll Wed Feb 8 16:14:11 2017
@@ -244,14 +244,49 @@ define i32 @test19(i1 %C) {
ret i32 %V
}
+; Add of sign bit -> xor of sign bit.
+
define i32 @test20(i32 %x) {
; CHECK-LABEL: @test20(
; CHECK-NEXT: ret i32 %x
;
- %tmp.2 = xor i32 %x, -2147483648
- ;; Add of sign bit -> xor of sign bit.
- %tmp.4 = add i32 %tmp.2, -2147483648
- ret i32 %tmp.4
+ %y = xor i32 %x, -2147483648
+ %z = add nsw i32 %y, -2147483648
+ ret i32 %z
+}
+
+define i32 @xor_sign_bit(i32 %x) {
+; CHECK-LABEL: @xor_sign_bit(
+; CHECK-NEXT: [[ADD:%.*]] = add i32 %x, -2147483606
+; CHECK-NEXT: ret i32 [[ADD]]
+;
+ %xor = xor i32 %x, 2147483648
+ %add = add i32 %xor, 42
+ ret i32 %add
+}
+
+; Lose no-wrap info by converting to xor? %x is known non-negative
+; here, but not after converting to xor.
+
+define i8 @add_nsw_signbit(i8 %x) {
+; CHECK-LABEL: @add_nsw_signbit(
+; CHECK-NEXT: [[Y:%.*]] = xor i8 %x, -128
+; CHECK-NEXT: ret i8 [[Y]]
+;
+ %y = add nsw i8 %x, -128
+ ret i8 %y
+}
+
+; Lose no-wrap info by converting to xor? %x is known non-negative
+; (x < 128 unsigned), but not after converting to xor.
+
+define i8 @add_nuw_signbit(i8 %x) {
+; CHECK-LABEL: @add_nuw_signbit(
+; CHECK-NEXT: [[Y:%.*]] = xor i8 %x, -128
+; CHECK-NEXT: ret i8 [[Y]]
+;
+ %y = add nuw i8 %x, 128
+ ret i8 %y
}
define i1 @test21(i32 %x) {
Modified: llvm/trunk/test/Transforms/InstCombine/icmp-add.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/InstCombine/icmp-add.ll?rev=294524&r1=294523&r2=294524&view=diff
==============================================================================
--- llvm/trunk/test/Transforms/InstCombine/icmp-add.ll (original)
+++ llvm/trunk/test/Transforms/InstCombine/icmp-add.ll Wed Feb 8 16:14:11 2017
@@ -106,3 +106,27 @@ define <2 x i1> @slt_zero_add_nsw_splat_
ret <2 x i1> %cmp
}
+; FIXME: InstCombine should not lose wrapping information by changing the add to xor.
+
+define i1 @slt_zero_add_nsw_signbit(i8 %x) {
+; CHECK-LABEL: @slt_zero_add_nsw_signbit(
+; CHECK-NEXT: [[Z:%.*]] = icmp sgt i8 %x, -1
+; CHECK-NEXT: ret i1 [[Z]]
+;
+ %y = add nsw i8 %x, -128
+ %z = icmp slt i8 %y, 0
+ ret i1 %z
+}
+
+; FIXME: InstCombine should not lose wrapping information by changing the add to xor.
+
+define i1 @slt_zero_add_nuw_signbit(i8 %x) {
+; CHECK-LABEL: @slt_zero_add_nuw_signbit(
+; CHECK-NEXT: [[Z:%.*]] = icmp sgt i8 %x, -1
+; CHECK-NEXT: ret i1 [[Z]]
+;
+ %y = add nuw i8 %x, 128
+ %z = icmp slt i8 %y, 0
+ ret i1 %z
+}
+
Modified: llvm/trunk/test/Transforms/InstCombine/sub-xor.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/InstCombine/sub-xor.ll?rev=294524&r1=294523&r2=294524&view=diff
==============================================================================
--- llvm/trunk/test/Transforms/InstCombine/sub-xor.ll (original)
+++ llvm/trunk/test/Transforms/InstCombine/sub-xor.ll Wed Feb 8 16:14:11 2017
@@ -48,13 +48,3 @@ define i32 @test3(i32 %x) {
ret i32 %add
}
-define i32 @test4(i32 %x) {
-; CHECK-LABEL: @test4(
-; CHECK-NEXT: [[ADD:%.*]] = add i32 %x, -2147483606
-; CHECK-NEXT: ret i32 [[ADD]]
-;
- %sub = xor i32 %x, 2147483648
- %add = add i32 %sub, 42
- ret i32 %add
-}
-
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