[NFC][msan] Workaround arg evaluation order diff GCC vs Clang (#113378)

Author: vitalybuka

llvm/lib/Transforms/Instrumentation/MemorySanitizer.cpp

@@ -2750,12 +2750,12 @@ struct MemorySanitizerVisitor : public InstVisitor<MemorySanitizerVisitor> {
     // its undefined bits. Let [b0, b1] be the interval of possible values of B.
     // Then (A cmp B) is defined iff (a0 cmp b1) == (a1 cmp b0).
     bool IsSigned = I.isSigned();
-    Value *S1 = IRB.CreateICmp(I.getPredicate(),
-                               getLowestPossibleValue(IRB, A, Sa, IsSigned),
-                               getHighestPossibleValue(IRB, B, Sb, IsSigned));
-    Value *S2 = IRB.CreateICmp(I.getPredicate(),
-                               getHighestPossibleValue(IRB, A, Sa, IsSigned),
-                               getLowestPossibleValue(IRB, B, Sb, IsSigned));
+    Value *Amin = getLowestPossibleValue(IRB, A, Sa, IsSigned);
+    Value *Bmax = getHighestPossibleValue(IRB, B, Sb, IsSigned);
+    Value *S1 = IRB.CreateICmp(I.getPredicate(), Amin, Bmax);
+    Value *Amax = getHighestPossibleValue(IRB, A, Sa, IsSigned);
+    Value *Bmin = getLowestPossibleValue(IRB, B, Sb, IsSigned);
+    Value *S2 = IRB.CreateICmp(I.getPredicate(), Amax, Bmin);
     Value *Si = IRB.CreateXor(S1, S2);
     setShadow(&I, Si);
     setOriginForNaryOp(I);