ValueTracking/test: cover known bits of mul

[artagnon]

No description provided.

[llvmbot]

@llvm/pr-subscribers-llvm-analysis

Author: Ramkumar Ramachandra (artagnon)

Changes

---

Full diff: https://github.com/llvm/llvm-project/pull/113050.diff

1 Files Affected:

• (added) llvm/test/Analysis/ValueTracking/knownbits-mul.ll (+152)

diff --git a/llvm/test/Analysis/ValueTracking/knownbits-mul.ll b/llvm/test/Analysis/ValueTracking/knownbits-mul.ll
new file mode 100644
index 00000000000000..79df43c99744e6
--- /dev/null
+++ b/llvm/test/Analysis/ValueTracking/knownbits-mul.ll
@@ -0,0 +1,152 @@
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py UTC_ARGS: --version 5
+; RUN: opt < %s -passes=instcombine -S | FileCheck %s
+
+define i8 @mul_low_bits_know(i8 %xx, i8 %yy) {
+; CHECK-LABEL: define i8 @mul_low_bits_know(
+; CHECK-SAME: i8 [[XX:%.*]], i8 [[YY:%.*]]) {
+; CHECK-NEXT:    ret i8 0
+;
+  %x = and i8 %xx, 2
+  %y = and i8 %yy, 4
+  %mul = mul i8 %x, %y
+  %r = and i8 %mul, 6
+  ret i8 %r
+}
+
+define i8 @mul_low_bits_know2(i8 %xx, i8 %yy) {
+; CHECK-LABEL: define i8 @mul_low_bits_know2(
+; CHECK-SAME: i8 [[XX:%.*]], i8 [[YY:%.*]]) {
+; CHECK-NEXT:    ret i8 0
+;
+  %x = or i8 %xx, -2
+  %y = and i8 %yy, 4
+  %mul = mul i8 %x, %y
+  %r = and i8 %mul, 2
+  ret i8 %r
+}
+
+define i8 @mul_low_bits_partially_known(i8 %xx, i8 %yy) {
+; CHECK-LABEL: define i8 @mul_low_bits_partially_known(
+; CHECK-SAME: i8 [[XX:%.*]], i8 [[YY:%.*]]) {
+; CHECK-NEXT:    [[Y:%.*]] = or i8 [[YY]], 2
+; CHECK-NEXT:    [[MUL:%.*]] = sub nsw i8 0, [[Y]]
+; CHECK-NEXT:    [[R:%.*]] = and i8 [[MUL]], 2
+; CHECK-NEXT:    ret i8 [[R]]
+;
+  %x = or i8 %xx, -4
+  %x.notsmin = or i8 %x, 3
+  %y = or i8 %yy, -2
+  %mul = mul i8 %x.notsmin, %y
+  %r = and i8 %mul, 6
+  ret i8 %r
+}
+
+define i8 @mul_low_bits_unknown(i8 %xx, i8 %yy) {
+; CHECK-LABEL: define i8 @mul_low_bits_unknown(
+; CHECK-SAME: i8 [[XX:%.*]], i8 [[YY:%.*]]) {
+; CHECK-NEXT:    [[X:%.*]] = or i8 [[XX]], 4
+; CHECK-NEXT:    [[Y:%.*]] = or i8 [[YY]], 6
+; CHECK-NEXT:    [[MUL:%.*]] = mul i8 [[X]], [[Y]]
+; CHECK-NEXT:    [[R:%.*]] = and i8 [[MUL]], 6
+; CHECK-NEXT:    ret i8 [[R]]
+;
+  %x = or i8 %xx, -4
+  %y = or i8 %yy, -2
+  %mul = mul i8 %x, %y
+  %r = and i8 %mul, 6
+  ret i8 %r
+}
+
+define i8 @mul_high_bits_know(i8 %xx, i8 %yy) {
+; CHECK-LABEL: define i8 @mul_high_bits_know(
+; CHECK-SAME: i8 [[XX:%.*]], i8 [[YY:%.*]]) {
+; CHECK-NEXT:    ret i8 0
+;
+  %x = and i8 %xx, 2
+  %y = and i8 %yy, 4
+  %mul = mul i8 %x, %y
+  %r = and i8 %mul, 16
+  ret i8 %r
+}
+
+define i8 @mul_high_bits_know2(i8 %xx, i8 %yy) {
+; CHECK-LABEL: define i8 @mul_high_bits_know2(
+; CHECK-SAME: i8 [[XX:%.*]], i8 [[YY:%.*]]) {
+; CHECK-NEXT:    [[X:%.*]] = or i8 [[XX]], -2
+; CHECK-NEXT:    [[Y:%.*]] = and i8 [[YY]], 4
+; CHECK-NEXT:    [[Y_NONZERO:%.*]] = or disjoint i8 [[Y]], 1
+; CHECK-NEXT:    [[MUL:%.*]] = mul nsw i8 [[X]], [[Y_NONZERO]]
+; CHECK-NEXT:    [[R:%.*]] = and i8 [[MUL]], -16
+; CHECK-NEXT:    ret i8 [[R]]
+;
+  %x = or i8 %xx, -2
+  %y = and i8 %yy, 4
+  %y.nonzero = or i8 %y, 1
+  %mul = mul i8 %x, %y.nonzero
+  %r = and i8 %mul, -16
+  ret i8 %r
+}
+
+define i8 @mul_high_bits_know3(i8 %xx, i8 %yy) {
+; CHECK-LABEL: define i8 @mul_high_bits_know3(
+; CHECK-SAME: i8 [[XX:%.*]], i8 [[YY:%.*]]) {
+; CHECK-NEXT:    [[X:%.*]] = or i8 [[XX]], 124
+; CHECK-NEXT:    [[Y:%.*]] = or i8 [[YY]], 126
+; CHECK-NEXT:    [[MUL:%.*]] = mul i8 [[X]], [[Y]]
+; CHECK-NEXT:    [[R:%.*]] = and i8 [[MUL]], 112
+; CHECK-NEXT:    ret i8 [[R]]
+;
+  %x = or i8 %xx, -4
+  %y = or i8 %yy, -2
+  %mul = mul i8 %x, %y
+  %r = and i8 %mul, -16
+  ret i8 %r
+}
+
+define i8 @mul_high_bits_unknown(i8 %xx, i8 %yy) {
+; CHECK-LABEL: define i8 @mul_high_bits_unknown(
+; CHECK-SAME: i8 [[XX:%.*]], i8 [[YY:%.*]]) {
+; CHECK-NEXT:    [[X:%.*]] = and i8 [[XX]], 2
+; CHECK-NEXT:    [[Y:%.*]] = and i8 [[YY]], 4
+; CHECK-NEXT:    [[MUL:%.*]] = mul nuw nsw i8 [[X]], [[Y]]
+; CHECK-NEXT:    ret i8 [[MUL]]
+;
+  %x = and i8 %xx, 2
+  %y = and i8 %yy, 4
+  %mul = mul i8 %x, %y
+  %r = and i8 %mul, 8
+  ret i8 %r
+}
+
+define i8 @mul_high_bits_unknown2(i8 %xx, i8 %yy) {
+; CHECK-LABEL: define i8 @mul_high_bits_unknown2(
+; CHECK-SAME: i8 [[XX:%.*]], i8 [[YY:%.*]]) {
+; CHECK-NEXT:    [[X:%.*]] = or i8 [[XX]], -2
+; CHECK-NEXT:    [[Y:%.*]] = and i8 [[YY]], 4
+; CHECK-NEXT:    [[MUL:%.*]] = mul nsw i8 [[X]], [[Y]]
+; CHECK-NEXT:    [[R:%.*]] = and i8 [[MUL]], -16
+; CHECK-NEXT:    ret i8 [[R]]
+;
+  %x = or i8 %xx, -2
+  %y = and i8 %yy, 4
+  %mul = mul i8 %x, %y
+  %r = and i8 %mul, -16
+  ret i8 %r
+}
+
+; TODO: This can be reduced to zero.
+define i8 @mul_high_bits_unknown3(i8 %xx, i8 %yy) {
+; CHECK-LABEL: define i8 @mul_high_bits_unknown3(
+; CHECK-SAME: i8 [[XX:%.*]], i8 [[YY:%.*]]) {
+; CHECK-NEXT:    [[X:%.*]] = or i8 [[XX]], 28
+; CHECK-NEXT:    [[Y:%.*]] = or i8 [[YY]], 30
+; CHECK-NEXT:    [[MUL:%.*]] = mul i8 [[X]], [[Y]]
+; CHECK-NEXT:    [[R:%.*]] = and i8 [[MUL]], 16
+; CHECK-NEXT:    ret i8 [[R]]
+;
+  %x = or i8 %xx, -4
+  %y = or i8 %yy, -2
+  %mul = mul i8 %x, %y
+  %r = and i8 %mul, 16
+  ret i8 %r
+}

[goldsteinn]

Typically its nicer to have these as part of the PR, otherwise its hard to see if they are in fact appropriate.
But LGTM.

Also regarding the commit messages (particularly the [<Component>] practice, found the reference: https://llvm.org/docs/DeveloperPolicy.html#id18), can you start doing it?