CI1->getValue() != APInt::getLowBitsSet(CI1->getBitWidth(), NewWidth))
return 0;
+ // This is only really a signed overflow check if the inputs have been
+ // sign-extended; check for that condition. For example, if CI2 is 2^31 and
+ // the operands of the add are 64 bits wide, we need at least 33 sign bits.
+ unsigned NeededSignBits = CI1->getBitWidth() - NewWidth + 1;
+ if (IC.ComputeNumSignBits(A) < NeededSignBits ||
+ IC.ComputeNumSignBits(B) < NeededSignBits)
+ return 0;
+
// In order to replace the original add with a narrower
// llvm.sadd.with.overflow, the only uses allowed are the add-with-constant
// and truncates that discard the high bits of the add. Verify that this is
ret i64 %Q
}
+; CHECK: @test8
+; PR11438
+; This is @test1, but the operands are not sign-extended. Make sure
+; we don't transform this case.
+define i32 @test8(i64 %a, i64 %b) nounwind ssp {
+entry:
+; CHECK-NOT: llvm.sadd
+; CHECK: add i64 %a, %b
+; CHECK-NOT: llvm.sadd
+; CHECK: ret
+ %add = add i64 %a, %b
+ %add.off = add i64 %add, 2147483648
+ %0 = icmp ugt i64 %add.off, 4294967295
+ br i1 %0, label %if.then, label %if.end
+
+if.then:
+ tail call void @throwAnExceptionOrWhatever() nounwind
+ br label %if.end
+if.end:
+ %conv9 = trunc i64 %add to i32
+ ret i32 %conv9
+}