Add an option to enable the SSA based peephole optimizer.

Eventually this pass will provide substantially better code in the interim between when we
have a crappy isel and nice isel.  Unfortunately doing so requires fixing the backend to
actually SUPPORT all of the fancy addressing modes that we now generate, and writing a DCE
pass for machine code.  Each of these is a fairly substantial job, so this will remain disabled
for the immediate future.  :(

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@10276 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/lib/Target/X86/X86.h b/lib/Target/X86/X86.h
index 5cf897fa7156d0959188d6c981f2a5f0c061a97c..c474d18ead3c74b243f500668e276578185fa6ec 100644 (file)
--- a/lib/Target/X86/X86.h
+++ b/lib/Target/X86/X86.h
@@ -34,6 +34,11 @@ FunctionPass *createX86SimpleInstructionSelector(TargetMachine &TM);
 ///
 FunctionPass *createX86PatternInstructionSelector(TargetMachine &TM);
 
+/// createX86SSAPeepholeOptimizerPass - Create a pass to perform SSA-based X86
+/// specific peephole optimizations.
+///
+FunctionPass *createX86SSAPeepholeOptimizerPass();
+
 /// createX86PeepholeOptimizer - Create a pass to perform X86 specific peephole
 /// optimizations.
 ///

diff --git a/lib/Target/X86/X86TargetMachine.cpp b/lib/Target/X86/X86TargetMachine.cpp
index 31eb4bd61c2df62a391cc78a58719e9402331205..eb4d19a7783e7b5ea82913e15bb8cdea05e373fa 100644 (file)
--- a/lib/Target/X86/X86TargetMachine.cpp
+++ b/lib/Target/X86/X86TargetMachine.cpp
@@ -29,6 +29,8 @@ namespace {
                          cl::desc("Print generated machine code"));
   cl::opt<bool> NoPatternISel("disable-pattern-isel", cl::init(true),
                         cl::desc("Use the 'simple' X86 instruction selector"));
+  cl::opt<bool> NoSSAPeephole("disable-ssa-peephole", cl::init(true),
+                        cl::desc("Disable the ssa-based peephole optimizer (defaults to disabled)"));
 }
 
 // allocateX86TargetMachine - Allocate and return a subclass of TargetMachine
@@ -66,9 +68,9 @@ bool X86TargetMachine::addPassesToEmitAssembly(PassManager &PM,
   else
     PM.add(createX86PatternInstructionSelector(*this));
 
-  // TODO: optional optimizations go here
-
-  // FIXME: Add SSA based peephole optimizer here.
+  // Run optional SSA-based machine code optimizations next...
+  if (!NoSSAPeephole)
+    PM.add(createX86SSAPeepholeOptimizerPass());
 
   // Print the instruction selected machine code...
   if (PrintCode)
@@ -117,7 +119,9 @@ bool X86TargetMachine::addPassesToJITCompile(FunctionPassManager &PM) {
   else
     PM.add(createX86PatternInstructionSelector(*this));
 
-  // TODO: optional optimizations go here
+  // Run optional SSA-based machine code optimizations next...
+  if (!NoSSAPeephole)
+    PM.add(createX86SSAPeepholeOptimizerPass());
 
   // FIXME: Add SSA based peephole optimizer here.