[llvm] r303750 - [InstCombine] add tests to document bitcast + bitwise-logic behavior; NFC
Sanjay Patel via llvm-commits
llvm-commits at lists.llvm.org
Wed May 24 07:21:31 PDT 2017
Author: spatel
Date: Wed May 24 09:21:31 2017
New Revision: 303750
URL: http://llvm.org/viewvc/llvm-project?rev=303750&view=rev
Log:
[InstCombine] add tests to document bitcast + bitwise-logic behavior; NFC
The solution for PR26702 ( https://bugs.llvm.org/show_bug.cgi?id=26702 )
added a canonicalization rule, but the minimal regression tests don't
demonstrate how that rule interacts with other folds.
Modified:
llvm/trunk/test/Transforms/InstCombine/bitcast.ll
Modified: llvm/trunk/test/Transforms/InstCombine/bitcast.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/InstCombine/bitcast.ll?rev=303750&r1=303749&r2=303750&view=diff
==============================================================================
--- llvm/trunk/test/Transforms/InstCombine/bitcast.ll (original)
+++ llvm/trunk/test/Transforms/InstCombine/bitcast.ll Wed May 24 09:21:31 2017
@@ -70,6 +70,51 @@ define <2 x i32> @or_bitcast_int_to_vec(
ret <2 x i32> %t2
}
+; PR26702 - https://bugs.llvm.org//show_bug.cgi?id=26702
+; Bitcast is canonicalized below logic, so we can see the not-not pattern.
+
+define <2 x i64> @is_negative(<4 x i32> %x) {
+; CHECK-LABEL: @is_negative(
+; CHECK-NEXT: [[LOBIT:%.*]] = ashr <4 x i32> %x, <i32 31, i32 31, i32 31, i32 31>
+; CHECK-NEXT: [[NOTNOT:%.*]] = bitcast <4 x i32> [[LOBIT]] to <2 x i64>
+; CHECK-NEXT: ret <2 x i64> [[NOTNOT]]
+;
+ %lobit = ashr <4 x i32> %x, <i32 31, i32 31, i32 31, i32 31>
+ %not = xor <4 x i32> %lobit, <i32 -1, i32 -1, i32 -1, i32 -1>
+ %bc = bitcast <4 x i32> %not to <2 x i64>
+ %notnot = xor <2 x i64> %bc, <i64 -1, i64 -1>
+ ret <2 x i64> %notnot
+}
+
+; This variation has an extra bitcast at the end. This means that the 2nd xor
+; can be done in <4 x i32> to eliminate a bitcast regardless of canonicalizaion.
+
+define <4 x i32> @is_negative_bonus_bitcast(<4 x i32> %x) {
+; CHECK-LABEL: @is_negative_bonus_bitcast(
+; CHECK-NEXT: [[LOBIT:%.*]] = ashr <4 x i32> %x, <i32 31, i32 31, i32 31, i32 31>
+; CHECK-NEXT: ret <4 x i32> [[LOBIT]]
+;
+ %lobit = ashr <4 x i32> %x, <i32 31, i32 31, i32 31, i32 31>
+ %not = xor <4 x i32> %lobit, <i32 -1, i32 -1, i32 -1, i32 -1>
+ %bc = bitcast <4 x i32> %not to <2 x i64>
+ %notnot = xor <2 x i64> %bc, <i64 -1, i64 -1>
+ %bc2 = bitcast <2 x i64> %notnot to <4 x i32>
+ ret <4 x i32> %bc2
+}
+
+; Negative test: bitcasts are canonicalized below bitwise logic. No changes here.
+
+define <2 x i8> @canonicalize_bitcast_logic_with_constant(<4 x i4> %x) {
+; CHECK-LABEL: @canonicalize_bitcast_logic_with_constant(
+; CHECK-NEXT: [[A:%.*]] = and <4 x i4> %x, <i4 0, i4 -8, i4 0, i4 -8>
+; CHECK-NEXT: [[B:%.*]] = bitcast <4 x i4> [[A]] to <2 x i8>
+; CHECK-NEXT: ret <2 x i8> [[B]]
+;
+ %a = and <4 x i4> %x, <i4 0, i4 8, i4 0, i4 8>
+ %b = bitcast <4 x i4> %a to <2 x i8>
+ ret <2 x i8> %b
+}
+
; PR27925 - https://llvm.org/bugs/show_bug.cgi?id=27925
define <4 x i32> @bitcasts_and_bitcast(<4 x i32> %a, <8 x i16> %b) {
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