Attempt fpcvt simplification per John Morgan.

3836425+corob-msft@users.noreply.github.com · 3836425+corob-msft@users.noreply.github.com · commit 65caf8244a3d · 2021-11-30T14:42:30.000-08:00
diff --git a/docs/build/reference/fpcvt.md b/docs/build/reference/fpcvt.md
@@ -30,9 +30,9 @@ In Visual Studio 2019 version 16.8 and later versions, the **`/fpcvt`** compiler
 
 For Visual Studio 2019, the default behavior for x64 targets is consistent with **`/fpcvt:BC`** unless **`/arch:AVX512`** is specified. Usually, the behavior for x86 targets is consistent with **`/fpcvt:IA`**, except under **`/arch:IA32`**, **`/arch:SSE`**, or sometimes where the result of a function call is directly converted to an unsigned integer. Use of **`/fpcvt`** overrides the default, so all conversions are handled consistently on either target. The behavior of conversions for ARM and ARM64 targets isn't consistent with either **`/fpcvt:BC`** or **`/fpcvt:IA`**.
 
-Standard C++ specifies that if a floating-point value can be truncated to a value that can be exactly represented in an integer type, conversion of that floating-point value to that integer type must return the truncated value. Otherwise, any behavior at all is allowed. Both **`/fpcvt`** options conform with Standard C++. The only difference is in what values are returned for invalid source values.
+Standard C++ specifies that if a truncated floating-point value is exactly representable in an integer type, it must have that value when converted to that type. Otherwise, any behavior at all is allowed. Both **`/fpcvt`** options conform with Standard C++. The only difference is in what values are returned for invalid source values.
 
-The **`/fpcvt:IA`** option causes any invalid conversion to return a single *sentinel* value, which is the destination value farthest from zero. For conversion to signed types, the sentinel is the minimum value for that type. Unsigned types use the maximum value. Floating-point operations may return a Not-a-Number (NaN) value to indicate an invalid operation. That's not an option for conversion to integer types, which don't have NaN values. The sentinel is used as a proxy for a NaN value, although it can also be the result of a valid conversion.
+The **`/fpcvt:IA`** option causes any invalid conversion to return a single *sentinel* value, which is the destination value farthest from zero. For conversion to signed types, the sentinel is the minimum value for that type. Unsigned types use the maximum value. Floating-point operations may return a Not-a-Number (NaN) value to indicate an invalid operation. That indicator isn't an option for conversion to integer types, which don't have NaN values. The sentinel is used as a proxy for a NaN value, although it can also be the result of a valid conversion.
 
 The **`/fpcvt:BC`** option also makes conversion to signed types return the minimum possible value when the source is invalid. However, conversion to unsigned integer types is based on conversion to **`long long`**. To convert a value to **`unsigned int`**, the compiler first converts it to type **`long long`**. The compiler then truncates the result to 32 bits. To convert a value to **`unsigned long long`**, valid source values that are too high for a **`long long`** are handled as a special case. All other values are first converted to **`long long`** and then recast to **`unsigned long long`**.
 
