[builtins] Fix -Wshift-count-overflow warnings for targets with 16-bit int

[uabelho]

Summary

Without this fix we got warnings like
/repo/llvm/compiler-rt/lib/builtins/floattidf.c:67:29: warning: shift count >= width of type [-Wshift-count-overflow]

((e + 1023) << 20) |              // exponent
            ^  ~~

1 warning generated.
when compiling for a target with 16-bit int.

In floatundisf.c the type of "e" was already changed to "si_int" in
https://reviews.llvm.org/D78662, now we do the same in a couple
of other files where "e" is also left shifted 20/23 steps.

[efriedma]

LGTM

compiler-rt/lib/builtins/floattidf.c

 
 COMPILER_RT_ABI double __floattidf(ti_int a) {
   if (a == 0)
     return 0.0;
   const unsigned N = sizeof(ti_int) * CHAR_BIT;
   const ti_int s = a >> (N - 1);
   a = (a ^ s) - s;
   int sd = N - __clzti2(a); // number of significant digits
-  int e = sd - 1;           // exponent
+  si_int e = sd - 1;        // exponent
   if (sd > DBL_MANT_DIG) {
     // start:  0000000000000000000001xxxxxxxxxxxxxxxxxxxxxxPQxxxxxxxxxxxxxxxxxx
     //  finish: 000000000000000000000000000000000000001xxxxxxxxxxxxxxxxxxxxxxPQR
     //                                               12345678901234567890123456
     // 1 = msb 1 bit
     // P = bit DBL_MANT_DIG-1 bits to the right of 1
     // Q = bit DBL_MANT_DIG bits to the right of 1
     // R = "or" of all bits to the right of Q

compiler-rt/lib/builtins/floattisf.c

 
 COMPILER_RT_ABI float __floattisf(ti_int a) {
   if (a == 0)
     return 0.0F;
   const unsigned N = sizeof(ti_int) * CHAR_BIT;
   const ti_int s = a >> (N - 1);
   a = (a ^ s) - s;
   int sd = N - __clzti2(a); // number of significant digits
-  int e = sd - 1;           // exponent
+  si_int e = sd - 1;        // exponent
   if (sd > FLT_MANT_DIG) {
     //  start:  0000000000000000000001xxxxxxxxxxxxxxxxxxxxxxPQxxxxxxxxxxxxxxxxxx
     // finish: 000000000000000000000000000000000000001xxxxxxxxxxxxxxxxxxxxxxPQR
     //                                                12345678901234567890123456
     //  1 = msb 1 bit
     //  P = bit FLT_MANT_DIG-1 bits to the right of 1
     //  Q = bit FLT_MANT_DIG bits to the right of 1
     //  R = "or" of all bits to the right of Q

compiler-rt/lib/builtins/floatuntidf.c

 // seee eeee eeee mmmm mmmm mmmm mmmm mmmm | mmmm mmmm mmmm mmmm mmmm mmmm mmmm
 // mmmm
 
 COMPILER_RT_ABI double __floatuntidf(tu_int a) {
   if (a == 0)
     return 0.0;
   const unsigned N = sizeof(tu_int) * CHAR_BIT;
   int sd = N - __clzti2(a); // number of significant digits
-  int e = sd - 1;           // exponent
+  si_int e = sd - 1;        // exponent
   if (sd > DBL_MANT_DIG) {
     //  start:  0000000000000000000001xxxxxxxxxxxxxxxxxxxxxxPQxxxxxxxxxxxxxxxxxx
     //  finish: 000000000000000000000000000000000000001xxxxxxxxxxxxxxxxxxxxxxPQR
     //                                                12345678901234567890123456
     //  1 = msb 1 bit
     //  P = bit DBL_MANT_DIG-1 bits to the right of 1
     //  Q = bit DBL_MANT_DIG bits to the right of 1
     //  R = "or" of all bits to the right of Q

compiler-rt/lib/builtins/floatuntisf.c

 
 // seee eeee emmm mmmm mmmm mmmm mmmm mmmm
 
 COMPILER_RT_ABI float __floatuntisf(tu_int a) {
   if (a == 0)
     return 0.0F;
   const unsigned N = sizeof(tu_int) * CHAR_BIT;
   int sd = N - __clzti2(a); // number of significant digits
-  int e = sd - 1;           // exponent
+  si_int e = sd - 1;        // exponent
   if (sd > FLT_MANT_DIG) {
     //  start:  0000000000000000000001xxxxxxxxxxxxxxxxxxxxxxPQxxxxxxxxxxxxxxxxxx
     //  finish: 000000000000000000000000000000000000001xxxxxxxxxxxxxxxxxxxxxxPQR
     //                                                12345678901234567890123456
     //  1 = msb 1 bit
     //  P = bit FLT_MANT_DIG-1 bits to the right of 1
     //  Q = bit FLT_MANT_DIG bits to the right of 1
     //  R = "or" of all bits to the right of Q