Cache common constants before lowering.

src/IceTargetLowering.h

Index: src/IceTargetLowering.h
diff --git a/src/IceTargetLowering.h b/src/IceTargetLowering.h
index 86721a20dd87012c94e5091c2c3d98a866dc345f..2acc39439772e65d6ad731915b89d3507fee4f44 100644
--- a/src/IceTargetLowering.h
+++ b/src/IceTargetLowering.h
@@ -28,6 +28,7 @@
 #include "IceCfgNode.h"
 #include "IceInst.h" // for the names of the Inst subtypes
 #include "IceOperand.h"
+#include "IceTargetLowering.def"
 #include "IceTypes.h"
 
 #include <utility>
@@ -461,8 +462,15 @@ protected:
   /// with the largest alignment need are placed in the front of the Dest list.
   void sortVarsByAlignment(VarList &Dest, const VarList &Source) const;
 
-  /// Make a call to an external helper function.
-  InstCall *makeHelperCall(const IceString &Name, Variable *Dest,
+  // Runtime helper function names

[Karl, 2016/03/16 22:50:52]

Also moved this enum to global context, so that we can move
getRuntimeHelperFunc() to global context.

+  enum RuntimeHelperFuncKind {
+#define X(Tag, Name) H_##Tag,
+    RUNTIME_HELPER_FUNCTIONS_TABLE
+#undef X
+        H_Num
+  };
+
+  InstCall *makeHelperCall(RuntimeHelperFuncKind Target, Variable *Dest,
                            SizeT MaxSrcs);
 
   void _set_dest_redefined() { Context.getLastInserted()->setDestRedefined(); }
@@ -569,44 +577,29 @@ protected:
   LoweringContext Context;
   const SandboxType SandboxingType = ST_None;
 
-  // Runtime helper function names
-  const static constexpr char *H_bitcast_16xi1_i16 = "__Sz_bitcast_16xi1_i16";
-  const static constexpr char *H_bitcast_8xi1_i8 = "__Sz_bitcast_8xi1_i8";
-  const static constexpr char *H_bitcast_i16_16xi1 = "__Sz_bitcast_i16_16xi1";
-  const static constexpr char *H_bitcast_i8_8xi1 = "__Sz_bitcast_i8_8xi1";
-  const static constexpr char *H_call_ctpop_i32 = "__popcountsi2";
-  const static constexpr char *H_call_ctpop_i64 = "__popcountdi2";
-  const static constexpr char *H_call_longjmp = "longjmp";
-  const static constexpr char *H_call_memcpy = "memcpy";
-  const static constexpr char *H_call_memmove = "memmove";
-  const static constexpr char *H_call_memset = "memset";
-  const static constexpr char *H_call_read_tp = "__nacl_read_tp";
-  const static constexpr char *H_call_setjmp = "setjmp";
-  const static constexpr char *H_fptosi_f32_i64 = "__Sz_fptosi_f32_i64";
-  const static constexpr char *H_fptosi_f64_i64 = "__Sz_fptosi_f64_i64";
-  const static constexpr char *H_fptoui_4xi32_f32 = "__Sz_fptoui_4xi32_f32";
-  const static constexpr char *H_fptoui_f32_i32 = "__Sz_fptoui_f32_i32";
-  const static constexpr char *H_fptoui_f32_i64 = "__Sz_fptoui_f32_i64";
-  const static constexpr char *H_fptoui_f64_i32 = "__Sz_fptoui_f64_i32";
-  const static constexpr char *H_fptoui_f64_i64 = "__Sz_fptoui_f64_i64";
-  const static constexpr char *H_frem_f32 = "fmodf";
-  const static constexpr char *H_frem_f64 = "fmod";
+  /// Returns constant zero of Ty.

[Jim Stichnoth, 2016/03/10 00:24:46]

You should probably also try to capture the calls to
Ctx->getConstantInt{1,8,16,32,64}(0).  That would capture all the integer zeroes
that appear directly in the pexe.

Optionally, capture the lookups of 0.0, but that is slightly tricky because you
want to match +0.0 and not -0.0.

[Karl, 2016/03/16 22:50:52]

The plan was to capture more constants. This CL was to set up the framework for
extending to other constants. Did add additional code to capture cached values
for the different called paths for constants.

Also added "i1 true" to the list of cached constants.

+  Constant *getConstantZero(Type Ty) const {
+    assert(Ty < IceType_NUM);
+    if (Constant *Result = ConstZeroForType[Ty])
+      return Result;
+    return Ctx->getConstantZero(Ty);
+  }
+
+  /// Returns the constant defining the corresponding runtime helper function.
+  Constant *getRuntimeHelperFunc(RuntimeHelperFuncKind Kind) const {

[Karl, 2016/03/16 22:50:52]

Moved this to global context, and modified body (here) to simply call the
version in the global context.

+    assert(Kind < H_Num);
+    Constant *Result = RuntimeHelperFunc[Kind];
+    assert(Result != nullptr && "No such runtime helper function");
+    return Result;
+  }
+
   const static constexpr char *H_getIP_prefix = "__Sz_getIP_";
-  const static constexpr char *H_sdiv_i32 = "__divsi3";
-  const static constexpr char *H_sdiv_i64 = "__divdi3";
-  const static constexpr char *H_sitofp_i64_f32 = "__Sz_sitofp_i64_f32";
-  const static constexpr char *H_sitofp_i64_f64 = "__Sz_sitofp_i64_f64";
-  const static constexpr char *H_srem_i32 = "__modsi3";
-  const static constexpr char *H_srem_i64 = "__moddi3";
-  const static constexpr char *H_udiv_i32 = "__udivsi3";
-  const static constexpr char *H_udiv_i64 = "__udivdi3";
-  const static constexpr char *H_uitofp_4xi32_4xf32 = "__Sz_uitofp_4xi32_4xf32";
-  const static constexpr char *H_uitofp_i32_f32 = "__Sz_uitofp_i32_f32";
-  const static constexpr char *H_uitofp_i32_f64 = "__Sz_uitofp_i32_f64";
-  const static constexpr char *H_uitofp_i64_f32 = "__Sz_uitofp_i64_f32";
-  const static constexpr char *H_uitofp_i64_f64 = "__Sz_uitofp_i64_f64";
-  const static constexpr char *H_urem_i32 = "__umodsi3";
-  const static constexpr char *H_urem_i64 = "__umoddi3";
+
+private:
+  // Holds constant zero for each type.
+  static Constant *ConstZeroForType[IceType_NUM];

[John, 2016/03/09 23:26:56]

What do you think of making this array a non-static member of global context?
Constants are tied to global context anyways.

[Karl, 2016/03/16 22:50:52]

Moved to global context, and used as cache inside method getConstantZero().

+  // Holds the constants representing each runtime helper function.
+  static Constant *RuntimeHelperFunc[H_Num];

[Karl, 2016/03/16 22:50:52]

Also moved this array to global context (as non-static).

 };
 
 /// TargetDataLowering is used for "lowering" data including initializers for