[libclc] Improve __clc_min/max/clamp implementation (#172599)

Replace __clc_max/min with __clc_fmax/fmin in __clc_clamp. FP
__clc_min/max/clamp now lowers to @llvm.minimumnum/@llvm.maximumnum, and
integer clamp lowers to @llvm.umin/@llvm.umax. This reduce fcmp+select
chains and improving codegen. Example change to amdgcn--amdhsa.bc:
```
in function _Z5clamphhh:
    >   %4 = icmp ugt i8 %0, %2
        %4 = tail call noundef i8 @llvm.umax.i8(i8 %0, i8 %1)
    >   %6 = select i1 %4, i8 %2, i8 %5
    >   ret i8 %6
    <   %5 = tail call noundef i8 @llvm.umin.i8(i8 %2, i8 %4)
    <   ret i8 %5
in function _Z5clampddd:
  in block %3 / %3:
    >   %4 = fcmp ogt double %0, %2
    >   %5 = fcmp olt double %0, %1
    >   %6 = select i1 %5, double %1, double %0
    >   %7 = select i1 %4, double %2, double %6
    >   ret double %7
    <   %4 = tail call noundef double @llvm.maximumnum.f64(double %0, double %1)
    <   %5 = tail call noundef double @llvm.minimumnum.f64(double %4, double %2)
    <   ret double %5
```

Author: wenju-he

libclc/clc/lib/generic/shared/clc_clamp.cl

@@ -7,6 +7,8 @@
 //===----------------------------------------------------------------------===//
 
 #include <clc/internal/clc.h>
+#include <clc/shared/clc_max.h>
+#include <clc/shared/clc_min.h>
 
 #define __CLC_BODY <clc_clamp.inc>
 #include <clc/integer/gentype.inc>

libclc/clc/lib/generic/shared/clc_clamp.inc

@@ -9,14 +9,13 @@
 _CLC_OVERLOAD _CLC_DEF __CLC_GENTYPE __clc_clamp(__CLC_GENTYPE x,
                                                  __CLC_GENTYPE y,
                                                  __CLC_GENTYPE z) {
-  return (x > z ? z : (x < y ? y : x));
+  return __clc_min(__clc_max(x, y), z);
 }
 
 #ifndef __CLC_SCALAR
 _CLC_OVERLOAD _CLC_DEF __CLC_GENTYPE __clc_clamp(__CLC_GENTYPE x,
                                                  __CLC_SCALAR_GENTYPE y,
                                                  __CLC_SCALAR_GENTYPE z) {
-  return (x > (__CLC_GENTYPE)z ? (__CLC_GENTYPE)z
-                               : (x < (__CLC_GENTYPE)y ? (__CLC_GENTYPE)y : x));
+  return __clc_min(__clc_max(x, (__CLC_GENTYPE)y), (__CLC_GENTYPE)z);
 }
 #endif

libclc/clc/lib/generic/shared/clc_max.cl

@@ -7,6 +7,7 @@
 //===----------------------------------------------------------------------===//
 
 #include <clc/internal/clc.h>
+#include <clc/math/clc_fmax.h>
 
 #define __CLC_BODY <clc_max.inc>
 #include <clc/integer/gentype.inc>

libclc/clc/lib/generic/shared/clc_max.inc

@@ -6,6 +6,22 @@
 //
 //===----------------------------------------------------------------------===//
 
+#ifdef __CLC_FPSIZE
+
+_CLC_OVERLOAD _CLC_DEF __CLC_GENTYPE __clc_max(__CLC_GENTYPE a,
+                                               __CLC_GENTYPE b) {
+  return __clc_fmax(a, b);
+}
+
+#ifndef __CLC_SCALAR
+_CLC_OVERLOAD _CLC_DEF __CLC_GENTYPE __clc_max(__CLC_GENTYPE a,
+                                               __CLC_SCALAR_GENTYPE b) {
+  return __clc_fmax(a, b);
+}
+#endif // __CLC_SCALAR
+
+#else // __CLC_FPSIZE
+
 _CLC_OVERLOAD _CLC_DEF __CLC_GENTYPE __clc_max(__CLC_GENTYPE a,
                                                __CLC_GENTYPE b) {
   return (a > b ? a : b);
@@ -16,4 +32,6 @@ _CLC_OVERLOAD _CLC_DEF __CLC_GENTYPE __clc_max(__CLC_GENTYPE a,
                                                __CLC_SCALAR_GENTYPE b) {
   return (a > (__CLC_GENTYPE)b ? a : (__CLC_GENTYPE)b);
 }
-#endif
+#endif // __CLC_SCALAR
+
+#endif // __CLC_FPSIZE

libclc/clc/lib/generic/shared/clc_min.cl

@@ -7,6 +7,7 @@
 //===----------------------------------------------------------------------===//
 
 #include <clc/internal/clc.h>
+#include <clc/math/clc_fmin.h>
 
 #define __CLC_BODY <clc_min.inc>
 #include <clc/integer/gentype.inc>

libclc/clc/lib/generic/shared/clc_min.inc

@@ -6,6 +6,21 @@
 //
 //===----------------------------------------------------------------------===//
 
+#ifdef __CLC_FPSIZE
+_CLC_OVERLOAD _CLC_DEF __CLC_GENTYPE __clc_min(__CLC_GENTYPE a,
+                                               __CLC_GENTYPE b) {
+  return __clc_fmin(a, b);
+}
+
+#ifndef __CLC_SCALAR
+_CLC_OVERLOAD _CLC_DEF __CLC_GENTYPE __clc_min(__CLC_GENTYPE a,
+                                               __CLC_SCALAR_GENTYPE b) {
+  return __clc_fmin(a, b);
+}
+#endif // __CLC_SCALAR
+
+#else // __CLC_FPSIZE
+
 _CLC_OVERLOAD _CLC_DEF __CLC_GENTYPE __clc_min(__CLC_GENTYPE a,
                                                __CLC_GENTYPE b) {
   return (b < a ? b : a);
@@ -16,4 +31,6 @@ _CLC_OVERLOAD _CLC_DEF __CLC_GENTYPE __clc_min(__CLC_GENTYPE a,
                                                __CLC_SCALAR_GENTYPE b) {
   return (b < (__CLC_GENTYPE)a ? (__CLC_GENTYPE)b : a);
 }
-#endif
+#endif // __CLC_SCALAR
+
+#endif // __CLC_FPSIZE