Add --relax-float-ops and --convert-relaxed-to-half

Android.mk

@@ -89,6 +89,7 @@ SPVTOOLS_OPT_SRC_FILES := \
 		source/opt/composite.cpp \
 		source/opt/const_folding_rules.cpp \
 		source/opt/constants.cpp \
+		source/opt/convert_to_half_pass.cpp \
 		source/opt/copy_prop_arrays.cpp \
 		source/opt/dead_branch_elim_pass.cpp \
 		source/opt/dead_insert_elim_pass.cpp \
@@ -153,6 +154,7 @@ SPVTOOLS_OPT_SRC_FILES := \
 		source/opt/reduce_load_size.cpp \
 		source/opt/redundancy_elimination.cpp \
 		source/opt/register_pressure.cpp \
+		source/opt/relax_float_ops_pass.cpp \
 		source/opt/remove_duplicates_pass.cpp \
 		source/opt/replace_invalid_opc.cpp \
 		source/opt/scalar_analysis.cpp \

BUILD.gn

@@ -479,6 +479,8 @@ static_library("spvtools_opt") {
     "source/opt/const_folding_rules.h",
     "source/opt/constants.cpp",
     "source/opt/constants.h",
+    "source/opt/convert_to_half_pass.cpp",
+    "source/opt/convert_to_half_pass.h",
     "source/opt/copy_prop_arrays.cpp",
     "source/opt/copy_prop_arrays.h",
     "source/opt/dead_branch_elim_pass.cpp",
@@ -611,6 +613,8 @@ static_library("spvtools_opt") {
     "source/opt/reflect.h",
     "source/opt/register_pressure.cpp",
     "source/opt/register_pressure.h",
+    "source/opt/relax_float_ops_pass.cpp",
+    "source/opt/relax_float_ops_pass.h",
     "source/opt/remove_duplicates_pass.cpp",
     "source/opt/remove_duplicates_pass.h",
     "source/opt/replace_invalid_opc.cpp",

include/spirv-tools/optimizer.hpp

@@ -674,6 +674,22 @@ Optimizer::PassToken CreateLoopUnrollPass(bool fully_unroll, int factor = 0);
 // processed (see IsSSATargetVar for details).
 Optimizer::PassToken CreateSSARewritePass();
 
+// Create pass to convert relaxed precision instructions to half precision.
+// This pass converts as many relaxed float32 arithmetic operations to half as
+// possible. It converts any float32 operands to half if needed. It converts
+// any resulting half precision values back to float32 as needed. No variables
+// are changed. No image operations are changed.
+//
+// Best if run late since it will generate better code with unneeded function
+// scope loads and stores and composite inserts and extracts removed. Also best
+// if followed by instruction simplification, redundancy elimination and DCE.
+Optimizer::PassToken CreateConvertRelaxedToHalfPass();
+
+// Create relax float ops pass.
+// This pass decorates all float32 result instructions with RelaxedPrecision
+// if not already so decorated.
+Optimizer::PassToken CreateRelaxFloatOpsPass();
+
 // Create copy propagate arrays pass.
 // This pass looks to copy propagate memory references for arrays.  It looks
 // for specific code patterns to recognize array copies.

source/opt/CMakeLists.txt

@@ -27,6 +27,7 @@ set(SPIRV_TOOLS_OPT_SOURCES
   composite.h
   const_folding_rules.h
   constants.h
+  convert_to_half_pass.h
   copy_prop_arrays.h
   dead_branch_elim_pass.h
   dead_insert_elim_pass.h
@@ -93,6 +94,7 @@ set(SPIRV_TOOLS_OPT_SOURCES
   redundancy_elimination.h
   reflect.h
   register_pressure.h
+  relax_float_ops_pass.h
   remove_duplicates_pass.h
   replace_invalid_opc.h
   scalar_analysis.h
@@ -132,6 +134,7 @@ set(SPIRV_TOOLS_OPT_SOURCES
   composite.cpp
   const_folding_rules.cpp
   constants.cpp
+  convert_to_half_pass.cpp
   copy_prop_arrays.cpp
   dead_branch_elim_pass.cpp
   dead_insert_elim_pass.cpp
@@ -196,6 +199,7 @@ set(SPIRV_TOOLS_OPT_SOURCES
   reduce_load_size.cpp
   redundancy_elimination.cpp
   register_pressure.cpp
+  relax_float_ops_pass.cpp
   remove_duplicates_pass.cpp
   replace_invalid_opc.cpp
   scalar_analysis.cpp