[llvm] a56803b - [Analysis] fix cast in ValueTracking to allow constant expression

[Sanjay Patel via llvm-commits]

Author: Sanjay Patel
Date: 2021-12-20T17:16:47-05:00
New Revision: a56803b8f8df4f8d866f91d354b82ee9b62e9a60

URL: https://github.com/llvm/llvm-project/commit/a56803b8f8df4f8d866f91d354b82ee9b62e9a60
DIFF: https://github.com/llvm/llvm-project/commit/a56803b8f8df4f8d866f91d354b82ee9b62e9a60.diff

LOG: [Analysis] fix cast in ValueTracking to allow constant expression

The test would crash because a non-instruction negate op made it in here.

Fixes #51506

Added: 
    

Modified: 
    llvm/lib/Analysis/ValueTracking.cpp
    llvm/unittests/Analysis/ValueTrackingTest.cpp

Removed: 
    


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diff  --git a/llvm/lib/Analysis/ValueTracking.cpp b/llvm/lib/Analysis/ValueTracking.cpp
index 2585961977964..fc378f97de0b1 100644
--- a/llvm/lib/Analysis/ValueTracking.cpp
+++ b/llvm/lib/Analysis/ValueTracking.cpp
@@ -1154,7 +1154,7 @@ static void computeKnownBitsFromOperator(const Operator *I,
       // If the negate has an NSW flag we can assume the sign bit of the result
       // will be 0 because that makes abs(INT_MIN) undefined.
       if (match(RHS, m_Neg(m_Specific(LHS))) &&
-          Q.IIQ.hasNoSignedWrap(cast<Instruction>(RHS)))
+          Q.IIQ.hasNoSignedWrap(cast<OverflowingBinaryOperator>(RHS)))
         Known.Zero.setSignBit();
     }
 

diff  --git a/llvm/unittests/Analysis/ValueTrackingTest.cpp b/llvm/unittests/Analysis/ValueTrackingTest.cpp
index 593100cbcd434..0104d321f2c94 100644
--- a/llvm/unittests/Analysis/ValueTrackingTest.cpp
+++ b/llvm/unittests/Analysis/ValueTrackingTest.cpp
@@ -1711,6 +1711,20 @@ TEST_F(ComputeKnownBitsTest, ComputeKnownBitsGEPWithRangeNoOverlap) {
   EXPECT_EQ(Known.getMaxValue(), 575);
 }
 
+TEST_F(ComputeKnownBitsTest, ComputeKnownBitsCrash) {
+  parseAssembly(
+      "@g.a = external global i16, align 1\n"
+      "define i16 @test(i16 %i) {\n"
+      "entry:\n"
+      "  %0 = icmp slt i16 sub (i16 0, i16 trunc (i32 udiv (i32 ptrtoint (i16* @g.a to i32), i32 -1) to i16)), 0\n"
+      "  %A = select i1 %0, i16 trunc (i32 udiv (i32 ptrtoint (i16* @g.a to i32), i32 -1) to i16), i16 sub (i16 0, i16 trunc (i32 udiv (i32 ptrtoint (i16* @g.a to i32), i32 -1) to i16))\n"
+      "  ret i16 %A\n"
+      "}\n");
+  AssumptionCache AC(*F);
+  KnownBits Known = computeKnownBits(
+      A, M->getDataLayout(), /* Depth */ 0, &AC, F->front().getTerminator());
+}
+
 class IsBytewiseValueTest : public ValueTrackingTest,
                             public ::testing::WithParamInterface<
                                 std::pair<const char *, const char *>> {