GlobalISel: Correct example PartialMapping table

[arsenm]

Summary

When I try to use this, it seems like the second half needs
to start where the previous part left off.

[qcolombet]

Hi Matt,

You're right.

Your fix is actually not completely correct for the next comments too:

• The 2x seems weird since the two inputs are on different lines and we would think the comment is meant for this one line alone. Could you have this comment spans the two lines
• the example with the break down does not match what's in the array any more. You have to fix line 122 (add the partial 32-32) and lines 127-128 too reflect the indices changes.

Thanks for fixing this.
Quentin

[arsenm]

Try again

[qcolombet]

LGTM

[arsenm]

r349879

include/llvm/CodeGen/GlobalISel/RegisterBankInfo.h

public:
   /// E.g.,
   /// Let say we have a 32-bit add and a <2 x 32-bit> vadd. We
   /// can expand the
   /// <2 x 32-bit> add into 2 x 32-bit add.
   ///
   /// Currently the TableGen-like file would look like:
   /// \code
   /// PartialMapping[] = {
-  /// /*32-bit add*/ {0, 32, GPR},
-  /// /*2x32-bit add*/ {0, 32, GPR}, {0, 32, GPR}, // <-- Same entry 3x
+  /// /*32-bit add*/    {0, 32, GPR}, // Scalar entry repeated for first vec elt.
+  /// /*2x32-bit add*/  {0, 32, GPR}, {32, 32, GPR},
   /// /*<2x32-bit> vadd {0, 64, VPR}
   /// }; // PartialMapping duplicated.
   ///
   /// ValueMapping[] {
   ///   /*plain 32-bit add*/ {&PartialMapping[0], 1},
   ///   /*expanded vadd on 2xadd*/ {&PartialMapping[1], 2},
   ///   /*plain <2x32-bit> vadd*/ {&PartialMapping[3], 1}
   /// };
   /// \endcode
   ///
   /// With the array of pointer, we would have:
   /// \code
   /// PartialMapping[] = {
-  /// /*32-bit add*/ {0, 32, GPR},
+  /// /*32-bit add lower */ {0, 32, GPR},
+  /// /*32-bit add upper */ {32, 32, GPR},
   /// /*<2x32-bit> vadd {0, 64, VPR}
   /// }; // No more duplication.
   ///
   /// BreakDowns[] = {
   /// /*AddBreakDown*/ &PartialMapping[0],
-  /// /*2xAddBreakDown*/ &PartialMapping[0], &PartialMapping[0],
-  /// /*VAddBreakDown*/ &PartialMapping[1]
+  /// /*2xAddBreakDown*/ &PartialMapping[0], &PartialMapping[1],
+  /// /*VAddBreakDown*/ &PartialMapping[2]
   /// }; // Addresses of PartialMapping duplicated (smaller).
   ///
   /// ValueMapping[] {
   ///   /*plain 32-bit add*/ {&BreakDowns[0], 1},
   ///   /*expanded vadd on 2xadd*/ {&BreakDowns[1], 2},
   ///   /*plain <2x32-bit> vadd*/ {&BreakDowns[3], 1}
   /// };
   /// \endcode