[llvm] d781df2 - ValueTracking/test: cover known-high-bits of rem (#109006)

[via llvm-commits]

Author: Ramkumar Ramachandra
Date: 2024-09-26T16:08:51+01:00
New Revision: d781df2006374b4a825cf661045023e74adcba42

URL: https://github.com/llvm/llvm-project/commit/d781df2006374b4a825cf661045023e74adcba42
DIFF: https://github.com/llvm/llvm-project/commit/d781df2006374b4a825cf661045023e74adcba42.diff

LOG: ValueTracking/test: cover known-high-bits of rem (#109006)

There is an underlying bug in KnownBits, and we should theoretically be
able to determine the high-bits of an srem as shown in the test, just
like urem. In preparation to fix this bug, add pre-commit tests testing
high-bits of srem and urem.

Added: 
    llvm/test/Analysis/ValueTracking/knownbits-rem.ll

Modified: 
    

Removed: 
    llvm/test/Analysis/ValueTracking/knownbits-rem-lowbits.ll


################################################################################
diff  --git a/llvm/test/Analysis/ValueTracking/knownbits-rem-lowbits.ll b/llvm/test/Analysis/ValueTracking/knownbits-rem.ll
similarity index 65%
rename from llvm/test/Analysis/ValueTracking/knownbits-rem-lowbits.ll
rename to llvm/test/Analysis/ValueTracking/knownbits-rem.ll
index 0521c7130055fe..e5512fa71ae0e2 100644
--- a/llvm/test/Analysis/ValueTracking/knownbits-rem-lowbits.ll
+++ b/llvm/test/Analysis/ValueTracking/knownbits-rem.ll
@@ -12,6 +12,17 @@ define i8 @urem_low_bits_know(i8 %xx, i8 %yy) {
   ret i8 %r
 }
 
+define i8 @urem_high_bits_know(i8 %xx, i8 %yy) {
+; CHECK-LABEL: @urem_high_bits_know(
+; CHECK-NEXT:    ret i8 0
+;
+  %x = and i8 %xx, 2
+  %y = and i8 %yy, -4
+  %rem = urem i8 %x, %y
+  %r = and i8 %rem, 8
+  ret i8 %r
+}
+
 define i8 @urem_low_bits_know2(i8 %xx, i8 %yy) {
 ; CHECK-LABEL: @urem_low_bits_know2(
 ; CHECK-NEXT:    ret i8 2
@@ -91,6 +102,74 @@ define i8 @srem_low_bits_know2(i8 %xx, i8 %yy) {
   ret i8 %r
 }
 
+define i8 @srem_high_bits_know(i8 %xx, i8 %yy) {
+; CHECK-LABEL: @srem_high_bits_know(
+; CHECK-NEXT:    [[X:%.*]] = or i8 [[XX:%.*]], -2
+; CHECK-NEXT:    [[Y:%.*]] = and i8 [[YY:%.*]], -4
+; CHECK-NEXT:    [[REM:%.*]] = srem i8 [[X]], [[Y]]
+; CHECK-NEXT:    [[R:%.*]] = and i8 [[REM]], -2
+; CHECK-NEXT:    ret i8 [[R]]
+;
+  %x = or i8 %xx, -2
+  %y = and i8 %yy, -4
+  %rem = srem i8 %x, %y
+  %r = and i8 %rem, -2
+  ret i8 %r
+}
+
+define i8 @srem_high_bits_know2(i8 %xx, i8 %yy) {
+; CHECK-LABEL: @srem_high_bits_know2(
+; CHECK-NEXT:    [[X:%.*]] = and i8 [[XX:%.*]], 13
+; CHECK-NEXT:    [[Y:%.*]] = or i8 [[YY:%.*]], -4
+; CHECK-NEXT:    [[REM:%.*]] = srem i8 [[X]], [[Y]]
+; CHECK-NEXT:    [[R:%.*]] = and i8 [[REM]], 8
+; CHECK-NEXT:    ret i8 [[R]]
+;
+  %x = and i8 %xx, 13
+  %y = or i8 %yy, -4
+  %rem = srem i8 %x, %y
+  %r = and i8 %rem, 8
+  ret i8 %r
+}
+
+define i8 @srem_high_bits_know3(i8 %xx, i8 %yy) {
+; CHECK-LABEL: @srem_high_bits_know3(
+; CHECK-NEXT:    [[X:%.*]] = or i8 [[XX:%.*]], -13
+; CHECK-NEXT:    [[Y:%.*]] = and i8 [[YY:%.*]], 4
+; CHECK-NEXT:    [[REM:%.*]] = srem i8 [[X]], [[Y]]
+; CHECK-NEXT:    [[R:%.*]] = and i8 [[REM]], 8
+; CHECK-NEXT:    ret i8 [[R]]
+;
+  %x = or i8 %xx, -13
+  %y = and i8 %yy, 4
+  %rem = srem i8 %x, %y
+  %r = and i8 %rem, 8
+  ret i8 %r
+}
+
+define i8 @srem_high_bits_know4(i8 %xx, i8 %yy) {
+; CHECK-LABEL: @srem_high_bits_know4(
+; CHECK-NEXT:    ret i8 0
+;
+  %x = and i8 %xx, 4
+  %y = or i8 %yy, -13
+  %rem = srem i8 %x, %y
+  %r = and i8 %rem, 8
+  ret i8 %r
+}
+
+define i8 @srem_high_bits_know5(i8 %xx, i8 %yy) {
+; CHECK-LABEL: @srem_high_bits_know5(
+; CHECK-NEXT:    [[X:%.*]] = and i8 [[XX:%.*]], 2
+; CHECK-NEXT:    ret i8 [[X]]
+;
+  %x = and i8 %xx, 2
+  %y = and i8 %yy, 4
+  %rem = srem i8 %x, %y
+  %r = and i8 %rem, 2
+  ret i8 %r
+}
+
 define i8 @srem_todo_low_bits_partially_know_should_fold_out_srem(i8 %xx, i8 %yy) {
 ; CHECK-LABEL: @srem_todo_low_bits_partially_know_should_fold_out_srem(
 ; CHECK-NEXT:    [[X:%.*]] = or i8 [[XX:%.*]], 10