[PATCH] D21819: [Docs][CodeGenerator] Don't specify the number of operands in BuildMI

[Visoiu Mistrih Francis via llvm-commits]

thegameg created this revision.
thegameg added reviewers: dexonsmith, kparzysz, rnk.
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Since rL31947, MI constructors take a `TargetInstrDescriptor`, instead of an instruction and a number of operands. The documentation seems to be outdated.

http://reviews.llvm.org/D21819

Files:
  docs/CodeGenerator.rst
  include/llvm/CodeGen/MachineInstrBuilder.h

Index: include/llvm/CodeGen/MachineInstrBuilder.h
===================================================================
--- include/llvm/CodeGen/MachineInstrBuilder.h
+++ include/llvm/CodeGen/MachineInstrBuilder.h
@@ -10,7 +10,9 @@
 // This file exposes a function named BuildMI, which is useful for dramatically
 // simplifying how MachineInstr's are created.  It allows use of code like this:
 //
-//   M = BuildMI(X86::ADDrr8, 2).addReg(argVal1).addReg(argVal2);
+//   M = BuildMI(MBB, MI, DL, get(X86::ADD8rr), Dst)
+//           .addReg(argVal1)
+//           .addReg(argVal2);
 //
 //===----------------------------------------------------------------------===//
 
Index: docs/CodeGenerator.rst
===================================================================
--- docs/CodeGenerator.rst
+++ docs/CodeGenerator.rst
@@ -386,32 +386,26 @@
 .. code-block:: c++
 
   // Create a 'DestReg = mov 42' (rendered in X86 assembly as 'mov DestReg, 42')
-  // instruction.  The '1' specifies how many operands will be added.
-  MachineInstr *MI = BuildMI(X86::MOV32ri, 1, DestReg).addImm(42);
-
-  // Create the same instr, but insert it at the end of a basic block.
+  // instruction and insert it at the end of the given MachineBasicBlock.
   MachineBasicBlock &MBB = ...
-  BuildMI(MBB, X86::MOV32ri, 1, DestReg).addImm(42);
+  DebufLoc DL;
+  MachineInstr *MI = BuildMI(MBB, DL, get(X86::MOV32ri), DestReg).addImm(42);
 
   // Create the same instr, but insert it before a specified iterator point.
   MachineBasicBlock::iterator MBBI = ...
-  BuildMI(MBB, MBBI, X86::MOV32ri, 1, DestReg).addImm(42);
+  BuildMI(MBB, MBBI, DL, get(X86::MOV32ri), DestReg).addImm(42);
 
   // Create a 'cmp Reg, 0' instruction, no destination reg.
-  MI = BuildMI(X86::CMP32ri, 2).addReg(Reg).addImm(0);
+  MI = BuildMI(MBB, DL, get(X86::CMP32ri8)).addReg(Reg).addImm(42);
 
   // Create an 'sahf' instruction which takes no operands and stores nothing.
-  MI = BuildMI(X86::SAHF, 0);
+  MI = BuildMI(MBB, DL, get(X86::SAHF));
 
   // Create a self looping branch instruction.
-  BuildMI(MBB, X86::JNE, 1).addMBB(&MBB);
-
-The key thing to remember with the ``BuildMI`` functions is that you have to
-specify the number of operands that the machine instruction will take.  This
-allows for efficient memory allocation.  You also need to specify if operands
-default to be uses of values, not definitions.  If you need to add a definition
-operand (other than the optional destination register), you must explicitly mark
-it as such:
+  BuildMI(MBB, DL, get(X86::JNE)).addMBB(&MBB);
+
+If you need to add a definition operand (other than the optional destination
+register), you must explicitly mark it as such:
 
 .. code-block:: c++
 


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