[wasm] Introduce the TrapIf and TrapUnless operators to generate trap code.

src/compiler/instruction-selector-impl.h

Index: src/compiler/instruction-selector-impl.h
diff --git a/src/compiler/instruction-selector-impl.h b/src/compiler/instruction-selector-impl.h
index 6cb87ea0c06cd2ecff9da771ba60c997cb2c728b..3b0b7c038fb9089380b63bd14777704d87b0fcfd 100644
--- a/src/compiler/instruction-selector-impl.h
+++ b/src/compiler/instruction-selector-impl.h
@@ -5,14 +5,17 @@
 #ifndef V8_COMPILER_INSTRUCTION_SELECTOR_IMPL_H_
 #define V8_COMPILER_INSTRUCTION_SELECTOR_IMPL_H_
 
-#include "src/compiler/instruction.h"
 #include "src/compiler/instruction-selector.h"
+#include "src/compiler/instruction.h"
 #include "src/compiler/linkage.h"
 #include "src/compiler/schedule.h"
 #include "src/macro-assembler.h"
 
 namespace v8 {
 namespace internal {
+
+class SourcePosition;
+
 namespace compiler {
 
 // Helper struct containing data about a table or lookup switch.
@@ -345,10 +348,19 @@ class FlagsContinuation final {
     return FlagsContinuation(condition, result);
   }
 
+  // Creates a new flags continuation for a wasm trap.
+  static FlagsContinuation ForTrap(FlagsCondition condition,
+                                   Runtime::FunctionId trap_id,
+                                   SourcePosition* source_position,
+                                   Node* result) {
+    return FlagsContinuation(condition, trap_id, source_position, result);
+  }
+
   bool IsNone() const { return mode_ == kFlags_none; }
   bool IsBranch() const { return mode_ == kFlags_branch; }
   bool IsDeoptimize() const { return mode_ == kFlags_deoptimize; }
   bool IsSet() const { return mode_ == kFlags_set; }
+  bool IsTrap() const { return mode_ == kFlags_trap; }
   FlagsCondition condition() const {
     DCHECK(!IsNone());
     return condition_;
@@ -365,6 +377,14 @@ class FlagsContinuation final {
     DCHECK(IsSet());
     return frame_state_or_result_;
   }
+  int trap_id() const {
+    DCHECK(IsTrap());
+    return trap_id_;
+  }
+  SourcePosition* source_position() const {
+    DCHECK(IsTrap());
+    return source_position_;
+  }
   BasicBlock* true_block() const {
     DCHECK(IsBranch());
     return true_block_;
@@ -437,6 +457,16 @@ class FlagsContinuation final {
     DCHECK_NOT_NULL(result);
   }
 
+  FlagsContinuation(FlagsCondition condition, int32_t trap_id,
+                    SourcePosition* source_position, Node* result)
+      : mode_(kFlags_trap),
+        condition_(condition),
+        frame_state_or_result_(result),
+        trap_id_(trap_id),
+        source_position_(source_position) {
+    DCHECK_NOT_NULL(result);
+  }
+
   FlagsMode const mode_;
   FlagsCondition condition_;
   DeoptimizeReason reason_;      // Only value if mode_ == kFlags_deoptimize
@@ -444,6 +474,8 @@ class FlagsContinuation final {
                                  // or mode_ == kFlags_set.
   BasicBlock* true_block_;       // Only valid if mode_ == kFlags_branch.
   BasicBlock* false_block_;      // Only valid if mode_ == kFlags_branch.
+  int32_t trap_id_;              // Only valid if mode_ == kFlags_trap.

[titzer, 2016/12/12 14:21:33]

I wonder if we could squeeze this into a uint8_t and whether it would therefore
fit in the alignment with the first couple of fields here.

[ahaas, 2016/12/13 12:38:59]

trap_id_ contains a runtime::FunctionId, and there are more than 256 runtime
functions. Should we store the basic block pointers and trap_id +
source_position in a union so that they use the same memory? These values should
not be used together anyways.

+  SourcePosition* source_position_;  // Only valid if mode_ == kFlags_trap.
 };
 
 }  // namespace compiler