[llvm] ValueTracking/test: cover known bits of mul (PR #113050)

[via llvm-commits]

llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-llvm-analysis

Author: Ramkumar Ramachandra (artagnon)

<details>
<summary>Changes</summary>



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


1 Files Affected:

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


``````````diff
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
+}

``````````

</details>


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