fix unreachable 'break' and 'return' (-Wunreachable-code-*)

CMakeLists.txt

@@ -419,6 +419,9 @@ if (LLAMA_ALL_WARNINGS)
             -Wcast-qual
             -Wno-unused-function
         )
+        if (CMAKE_C_COMPILER_ID MATCHES "Clang")  # clang only
+            set(warning_flags ${warning_flags} -Wunreachable-code-break -Wunreachable-code-return)
+        endif()
         set(c_flags
             ${warning_flags}
             -Wdouble-promotion

Makefile

@@ -181,12 +181,13 @@ MK_CXXFLAGS  += $(WARN_FLAGS) -Wmissing-declarations -Wmissing-noreturn
 # TODO(cebtenzzre): remove this once PR #2632 gets merged
 TTFS_CXXFLAGS = $(CXXFLAGS) -Wno-missing-declarations
 
-ifneq '' '$(findstring clang,$(shell $(CXX) --version))'
+ifneq '' '$(findstring clang,$(shell $(CC) --version))'
-	# clang++ only
+	# clang only
-	MK_HOST_CXXFLAGS += -Wmissing-prototypes
+	MK_CFLAGS        += -Wunreachable-code-break -Wunreachable-code-return
+	MK_HOST_CXXFLAGS += -Wunreachable-code-break -Wunreachable-code-return -Wmissing-prototypes
 	TTFS_CXXFLAGS    += -Wno-missing-prototypes
 else
-	# g++ only
+	# gcc only
 	MK_HOST_CXXFLAGS += -Wno-format-truncation -Wno-array-bounds
 endif
 

common/common.cpp

@@ -712,10 +712,9 @@ std::string gpt_random_prompt(std::mt19937 & rng) {
         case 7: return "He";
         case 8: return "She";
         case 9: return "They";
-        default: return "To";
     }
 
-    return "The";
+    GGML_UNREACHABLE();
 }
 
 //

ggml.c

@@ -5071,31 +5071,31 @@ int32_t ggml_get_i32_1d(const struct ggml_tensor * tensor, int i) {
             {
                 GGML_ASSERT(tensor->nb[0] == sizeof(int8_t));
                 return ((int8_t *)(tensor->data))[i];
-            } break;
+            }
         case GGML_TYPE_I16:
             {
                 GGML_ASSERT(tensor->nb[0] == sizeof(int16_t));
                 return ((int16_t *)(tensor->data))[i];
-            } break;
+            }
         case GGML_TYPE_I32:
             {
                 GGML_ASSERT(tensor->nb[0] == sizeof(int32_t));
                 return ((int32_t *)(tensor->data))[i];
-            } break;
+            }
         case GGML_TYPE_F16:
             {
                 GGML_ASSERT(tensor->nb[0] == sizeof(ggml_fp16_t));
                 return GGML_FP16_TO_FP32(((ggml_fp16_t *)(tensor->data))[i]);
-            } break;
+            }
         case GGML_TYPE_F32:
             {
                 GGML_ASSERT(tensor->nb[0] == sizeof(float));
                 return ((float *)(tensor->data))[i];
-            } break;
+            }
         default:
             {
                 GGML_ASSERT(false);
-            } break;
+            }
     }
 
     return 0.0f;
@@ -5141,31 +5141,31 @@ float ggml_get_f32_1d(const struct ggml_tensor * tensor, int i) {
             {
                 GGML_ASSERT(tensor->nb[0] == sizeof(int8_t));
                 return ((int8_t *)(tensor->data))[i];
-            } break;
+            }
         case GGML_TYPE_I16:
             {
                 GGML_ASSERT(tensor->nb[0] == sizeof(int16_t));
                 return ((int16_t *)(tensor->data))[i];
-            } break;
+            }
         case GGML_TYPE_I32:
             {
                 GGML_ASSERT(tensor->nb[0] == sizeof(int32_t));
                 return ((int32_t *)(tensor->data))[i];
-            } break;
+            }
         case GGML_TYPE_F16:
             {
                 GGML_ASSERT(tensor->nb[0] == sizeof(ggml_fp16_t));
                 return GGML_FP16_TO_FP32(((ggml_fp16_t *)(tensor->data))[i]);
-            } break;
+            }
         case GGML_TYPE_F32:
             {
                 GGML_ASSERT(tensor->nb[0] == sizeof(float));
                 return ((float *)(tensor->data))[i];
-            } break;
+            }
         default:
             {
                 GGML_ASSERT(false);
-            } break;
+            }
     }
 
     return 0.0f;
@@ -18913,7 +18913,7 @@ static enum ggml_opt_result linesearch_backtracking(
         (*step) *= width;
     }
 
-    return GGML_LINESEARCH_FAIL;
+    GGML_UNREACHABLE();
 }
 
 static enum ggml_opt_result ggml_opt_lbfgs(
@@ -19165,7 +19165,7 @@ static enum ggml_opt_result ggml_opt_lbfgs(
         step[0] = 1.0;
     }
 
-    return GGML_OPT_DID_NOT_CONVERGE;
+    GGML_UNREACHABLE();
 }
 
 struct ggml_opt_params ggml_opt_default_params(enum ggml_opt_type type) {

ggml.h

@@ -248,6 +248,14 @@
         } \
     } while (0)
 
+#ifndef NDEBUG
+#define GGML_UNREACHABLE() GGML_ASSERT(!"statement should not be reached")
+#elif defined(__GNUC__)
+#define GGML_UNREACHABLE() __builtin_unreachable()
+#else
+#define GGML_UNREACHABLE() ((void) 0)
+#endif
+
 // used to copy the number of elements and stride in bytes of tensors into local variables.
 // main purpose is to reduce code duplication and improve readability.
 //