[clang] [llvm] [ConstantRange] Estimate tighter lower (upper) bounds for masked binary and (or) (PR #120352)

[Stephen Senran Zhang via llvm-commits]

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@@ -2720,6 +2720,22 @@ TEST_F(ConstantRangeTest, binaryAnd) {
   EXPECT_EQ(R16_32.binaryAnd(R0_99), R0_32);
   EXPECT_EQ(R0_99.binaryAnd(R16_32), R0_32);
 
+  // 'And' with leading bits are masked (with common leading bits stripped)
+  ConstantRange RMaskedL(APInt(8, 0b10'00101'1), APInt(8, 0b10'10000'0 + 1));
+  ConstantRange RMaskedR(APInt(8, 0b10'11111'0), APInt(8, 0b10'11111'1 + 1));
+  EXPECT_EQ(RMaskedL.binaryAnd(RMaskedR).getLower(), APInt(8, 0b10'00101'0));
+  EXPECT_EQ(RMaskedR.binaryAnd(RMaskedL).getLower(), APInt(8, 0b10'00101'0));
+
+  ConstantRange RMaskedL1(APInt(8, 0b00'011'010), APInt(8, 0b00'100'100 + 1));
+  ConstantRange RMaskedR1(APInt(8, 0b00'111'010), APInt(8, 0b00'111'110 + 1));
+  EXPECT_EQ(RMaskedL1.binaryAnd(RMaskedR1).getLower(), APInt(8, 0b00'011'000));
+  EXPECT_EQ(RMaskedR1.binaryAnd(RMaskedL1).getLower(), APInt(8, 0b00'011'000));
+
+  ConstantRange RMaskedL2(APInt(8, 0b0000'0111u), APInt(8, 0b0000'1101u + 1u));
+  ConstantRange RMaskedR2(APInt(8, 0xff), APInt(8, 0));
+  EXPECT_EQ(RMaskedL2.binaryAnd(RMaskedR2), RMaskedL2);
+  EXPECT_EQ(RMaskedR2.binaryAnd(RMaskedL2), RMaskedL2);
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zsrkmyn wrote:

So, should I `EXPECT_GE(lower, 0)` or `EXPECT_EQ(lower, 0)`? I prefer the former, because tests won't fail if the algorithm is further optimized.

https://github.com/llvm/llvm-project/pull/120352