Subzero: Rewrite the pass timing infrastructure.

This makes it much more useful for individual analysis and long-term translation performance tracking.

1. Collect and report aggregated across the entire translation, instead of function-by-function.  If you really care about a single function, just extract it and translate it separately for analysis.

2. Remove "-verbose time" and just use -timing.

3. Collects two kinds of timings: cumulative and flat.  Cumulative measures the total time, even if a callee also times itself.  Flat only measures the currently active timer at the top of the stack.  The flat times should add up to 100%, but cumulative will usually add up to much more than 100%.

BUG= none
R=jvoung@chromium.org

Review URL: https://codereview.chromium.org/610813002

Makefile.standalone

diff --git a/Makefile.standalone b/Makefile.standalone
index a913497..175dd12 100644
--- a/Makefile.standalone
+++ b/Makefile.standalone
@@ -80,9 +80,10 @@
 	IceMemoryRegion.cpp \
 	IceOperand.cpp \
 	IceRegAlloc.cpp \
-        IceRNG.cpp \
+	IceRNG.cpp \
 	IceTargetLowering.cpp \
 	IceTargetLoweringX8632.cpp \
+	IceTimerTree.cpp \
 	IceTranslator.cpp \
 	IceTypeConverter.cpp \
 	IceTypes.cpp \
@@ -113,7 +114,7 @@
 $(OBJDIR):
 	@mkdir -p $@
 
-check-lit: llvm2ice
+check-lit: llvm2ice make_symlink
 	LLVM_BIN_PATH=$(LLVM_BIN_PATH) \
 	$(LLVM_SRC_PATH)/utils/lit/lit.py -sv tests_lit