From 4ef3e45d7c6ec3c482a1a48f4df470811aa3cf0a Mon Sep 17 00:00:00 2001
From: buzbee <buzbee@google.com>
Date: Fri, 14 Dec 2012 13:35:28 -0800
Subject: Compiler constant handling rework

In preparation for de-optimization, reworked the constant
handling mechanism.  Also took advantage of knowledge of
constant operands (particularly for long operations).

Significant performance improvements for Mandelbrot
(~60 seconds to ~34 seconds).  Minor improvements in other
benchmarks.

The new constant handling breaks two of the existing
optimization passes: "Skip Large Method" and "Load/Store
Elimization."

I don't intend to update the large method optimization
because it will be superceeded by the upcoming interpreter/
fingerprinting mechanism.  Leaving the code in place for
now in order to compare compile-time improvements with
fingerprinting/interpret.  All related code will be deleted
when that is complete.

The load/store elimination pass needs some rework to handle
uses of multiple-register loads and stores.  It will be
updated & restored in a future CL.

Change-Id: Ia979abaf51b8ae81bbb0428031cbcea854625fac
---
 src/compiler/compiler_ir.h | 34 +++++++++++++++++++++++++++++++++-
 1 file changed, 33 insertions(+), 1 deletion(-)

(limited to 'src/compiler/compiler_ir.h')

diff --git a/src/compiler/compiler_ir.h b/src/compiler/compiler_ir.h
index aca32d5585..056c308c79 100644
--- a/src/compiler/compiler_ir.h
+++ b/src/compiler/compiler_ir.h
@@ -230,7 +230,8 @@ struct BasicBlock {
   bool catch_entry;
   bool explicit_throw;
   bool conditional_branch;
-  bool has_return;
+  bool has_return;                  // Contains a return.
+  bool dominates_return;            // Is a member of return extended basic block
   uint16_t start_offset;
   uint16_t nesting_depth;
   BBType block_type;
@@ -306,6 +307,7 @@ struct CompilationUnit {
       vreg_to_ssa_map(NULL),
       ssa_last_defs(NULL),
       is_constant_v(NULL),
+      must_flush_constant_v(NULL),
       constant_values(NULL),
       reg_location(NULL),
       promotion_map(NULL),
@@ -418,6 +420,7 @@ struct CompilationUnit {
   int* vreg_to_ssa_map;            // length == method->registers_size
   int* ssa_last_defs;              // length == method->registers_size
   ArenaBitVector* is_constant_v;   // length == num_ssa_reg
+  ArenaBitVector* must_flush_constant_v;   // length == num_ssa_reg
   int* constant_values;            // length == num_ssa_reg
 
   // Use counts of ssa names.
@@ -579,6 +582,35 @@ static const CodePattern special_patterns[] = {
   {{Instruction::RETURN_WIDE}, kIdentity},
 };
 
+static inline bool IsConst(const CompilationUnit* cu, int32_t s_reg)
+{
+  return (IsBitSet(cu->is_constant_v, s_reg));
+}
+
+static inline bool IsConst(const CompilationUnit* cu, RegLocation loc)
+{
+  return (IsConst(cu, loc.orig_sreg));
+}
+
+static inline int32_t ConstantValue(const CompilationUnit* cu, RegLocation loc)
+{
+  DCHECK(IsConst(cu, loc));
+  return cu->constant_values[loc.orig_sreg];
+}
+
+static inline int64_t ConstantValueWide(const CompilationUnit* cu, RegLocation loc)
+{
+  DCHECK(IsConst(cu, loc));
+  return (static_cast<int64_t>(cu->constant_values[loc.orig_sreg + 1]) << 32) |
+      Low32Bits(static_cast<int64_t>(cu->constant_values[loc.orig_sreg]));
+}
+
+static inline bool MustFlushConstant(const CompilationUnit* cu, RegLocation loc)
+{
+  DCHECK(IsConst(cu, loc));
+  return IsBitSet(cu->must_flush_constant_v, loc.orig_sreg);
+}
+
 }  // namespace art
 
 #endif // ART_SRC_COMPILER_COMPILER_IR_H_
-- 
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