[llvm] r318083 - Reorder Value.def to optimize code size

[Serge Guelton via llvm-commits]

Author: serge_sans_paille
Date: Mon Nov 13 12:57:40 2017
New Revision: 318083

URL: http://llvm.org/viewvc/llvm-project?rev=318083&view=rev
Log:
Reorder Value.def to optimize code size

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.

Differential Revision: https://reviews.llvm.org/D39373


Modified:
    llvm/trunk/include/llvm/IR/Value.def

Modified: llvm/trunk/include/llvm/IR/Value.def
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/IR/Value.def?rev=318083&r1=318082&r2=318083&view=diff
==============================================================================
--- llvm/trunk/include/llvm/IR/Value.def (original)
+++ llvm/trunk/include/llvm/IR/Value.def Mon Nov 13 12:57:40 2017
@@ -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<Constant> faster
+// and smaller by one operation.
 
+// Constant
 HANDLE_GLOBAL_VALUE(Function)
 HANDLE_GLOBAL_VALUE(GlobalAlias)
 HANDLE_GLOBAL_VALUE(GlobalIFunc)
@@ -88,13 +82,6 @@ HANDLE_CONSTANT(ConstantFP)
 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)
@@ -102,6 +89,24 @@ HANDLE_CONSTANT_MARKER(ConstantDataLastV
 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