[PATCH] D39373: Reorder Value.def to optimize code size

[serge via Phabricator via llvm-commits]

serge-sans-paille created this revision.

If the first values in Value.def is the range of constant, then the code generated by ``isa<Constant>`` is smaller by one operation (basically, an add is removed). It turns out this small optimization reduces the size of the statically linked clang binary by 400ko on my laptop. The theoritical performance gain is non visible from my benchmarks, but the size dropdown is.


Repository:
  rL LLVM

https://reviews.llvm.org/D39373

Files:
  include/llvm/IR/Value.def


Index: include/llvm/IR/Value.def
===================================================================
--- include/llvm/IR/Value.def
+++ include/llvm/IR/Value.def
@@ -56,16 +56,10 @@
 #define HANDLE_CONSTANT_MARKER(MarkerName, ValueName)
 #endif
 
-HANDLE_VALUE(Argument)
-HANDLE_VALUE(BasicBlock)
-
-// FIXME: It's awkward that Value.def knows about classes in Analysis. While
-// this doesn't introduce a strict link or include dependency, we should remove
-// the circular dependency eventually.
-HANDLE_MEMORY_VALUE(MemoryUse)
-HANDLE_MEMORY_VALUE(MemoryDef)
-HANDLE_MEMORY_VALUE(MemoryPhi)
+// Having constant first makes the range check for isa<Consant> faster
+// and smaller by one operation.
 
+// Constant
 HANDLE_GLOBAL_VALUE(Function)
 HANDLE_GLOBAL_VALUE(GlobalAlias)
 HANDLE_GLOBAL_VALUE(GlobalIFunc)
@@ -88,20 +82,31 @@
 HANDLE_CONSTANT(ConstantPointerNull)
 HANDLE_CONSTANT(ConstantTokenNone)
 
-HANDLE_METADATA_VALUE(MetadataAsValue)
-HANDLE_INLINE_ASM_VALUE(InlineAsm)
-
-HANDLE_INSTRUCTION(Instruction)
-// Enum values starting at InstructionVal are used for Instructions;
-// don't add new values here!
-
 HANDLE_CONSTANT_MARKER(ConstantFirstVal, Function)
 HANDLE_CONSTANT_MARKER(ConstantLastVal, ConstantTokenNone)
 HANDLE_CONSTANT_MARKER(ConstantDataFirstVal, UndefValue)
 HANDLE_CONSTANT_MARKER(ConstantDataLastVal, ConstantTokenNone)
 HANDLE_CONSTANT_MARKER(ConstantAggregateFirstVal, ConstantArray)
 HANDLE_CONSTANT_MARKER(ConstantAggregateLastVal, ConstantVector)
 
+HANDLE_VALUE(Argument)
+HANDLE_VALUE(BasicBlock)
+
+
+HANDLE_METADATA_VALUE(MetadataAsValue)
+HANDLE_INLINE_ASM_VALUE(InlineAsm)
+
+// FIXME: It's awkward that Value.def knows about classes in Analysis. While
+// this doesn't introduce a strict link or include dependency, we should remove
+// the circular dependency eventually.
+HANDLE_MEMORY_VALUE(MemoryUse)
+HANDLE_MEMORY_VALUE(MemoryDef)
+HANDLE_MEMORY_VALUE(MemoryPhi)
+
+HANDLE_INSTRUCTION(Instruction)
+// Enum values starting at InstructionVal are used for Instructions;
+// don't add new values here!
+
 #undef HANDLE_MEMORY_VALUE
 #undef HANDLE_GLOBAL_VALUE
 #undef HANDLE_CONSTANT


-------------- next part --------------
A non-text attachment was scrubbed...
Name: D39373.120608.patch
Type: text/x-patch
Size: 2136 bytes
Desc: not available
URL: <http://lists.llvm.org/pipermail/llvm-commits/attachments/20171027/ff5b8ae9/attachment.bin>