[MLIR][Presburger] Disambiguate call to floor

[ro]

Summary

While testing LLVM 14.0.0 rc1 on Solaris, compilation of FAILed with

/var/llvm/llvm-14.0.0-rc1/rc1/llvm-project/mlir/lib/Analysis/Presburger/Utils.cpp: In lambda function:
/var/llvm/llvm-14.0.0-rc1/rc1/llvm-project/mlir/lib/Analysis/Presburger/Utils.cpp:48:58: error: call of overloaded ‘floor(int64_t)’ is ambiguous
   48 |                  [gcd](int64_t &n) { return floor(n / gcd); });
      |                                                          ^
...
/usr/gcc/10/lib/gcc/sparcv9-sun-solaris2.11/10.3.0/include-fixed/iso/math_iso.h:201:21: note: candidate: ‘long double std::floor(long double)’
  201 |  inline long double floor(long double __X) { return __floorl(__X); }
      |                     ^~~~~
/usr/gcc/10/lib/gcc/sparcv9-sun-solaris2.11/10.3.0/include-fixed/iso/math_iso.h:165:15: note: candidate: ‘float std::floor(float)’
  165 |  inline float floor(float __X) { return __floorf(__X); }
      |               ^~~~~
/usr/gcc/10/lib/gcc/sparcv9-sun-solaris2.11/10.3.0/include-fixed/iso/math_iso.h:78:15: note: candidate: ‘double std::floor(double)’
   78 | extern double floor __P((double));
      |               ^~~~~

The same issue had already occured in the past, cf. D108750, and the solution is the same: cast the floor arg to double.

Tested on amd64-pc-solaris2.11 and sparcv9-sun-solaris2.11.

Obviously this should also be backported to the release/14.x branch.

[arjunp]

mlir/lib/Analysis/Presburger/Utils.cpp

48

This code should have used floorDiv to floor divide n by gcd. That also resolves the ambiguity issue, I think. If you would like to go ahead with the patch as-is for fixing the build, I'm also happy to fix the logic later in another patch.

[ro]

mlir/lib/Analysis/Presburger/Utils.cpp

48

I've decided to install the patch as is to quickly restore the build.

mlir/lib/Analysis/Presburger/Utils.cpp

static void normalizeDivisionByGCD(SmallVectorImpl<int64_t> &dividend,
   for (size_t i = 1, m = dividend.size() - 1; i < m; i++) {
     gcd = llvm::greatestCommonDivisor(std::abs(dividend[i]), gcd);
     if (gcd == 1)
       return;
   }
 
   // Normalize the dividend and the denominator.
   std::transform(dividend.begin(), dividend.end(), dividend.begin(),
-                 [gcd](int64_t &n) { return floor(n / gcd); });
+                 [gcd](int64_t &n) { return floor((double)(n / gcd)); });
   divisor /= gcd;
 }
 
 /// Check if the pos^th identifier can be represented as a division using upper
 /// bound inequality at position `ubIneq` and lower bound inequality at position
 /// `lbIneq`.
 ///
 /// Let `id` be the pos^th identifier, then `id` is equivalent to