commit ac878fcbdd644d5feecd7efe404d362081f5575b
author alan-baker <33432579+alan-baker@users.noreply.github.com> Wed Apr 17 18:21:19 2019 -0400
committer GitHub <noreply@github.com> Wed Apr 17 18:21:19 2019 -0400
tree 24fbf3c5be53f29855d8f2b372212cd7ede1183f
parent 21712068feeef8a5d3807f79ba714175a5a9629c

Remove unreachable block validation (#2525)

* Remove the check that blocks terminated by OpUnreachable are not
statically reachable in the CFG
* Updated tests

source/val/validate_cfg.cpp

diff --git a/source/val/validate_cfg.cpp b/source/val/validate_cfg.cpp
index 1d6f920..6e7acbd 100644
--- a/source/val/validate_cfg.cpp
+++ b/source/val/validate_cfg.cpp
@@ -725,36 +725,6 @@
   return SPV_SUCCESS;
 }
 
-// Checks that there are no OpUnreachable instructions reachable from the entry
-// block of |function|.
-spv_result_t ValidateUnreachableBlocks(ValidationState_t& _,
-                                       Function& function) {
-  auto* entry_block = function.first_block();
-  std::vector<BasicBlock*> stack;
-  std::unordered_set<BasicBlock*> seen;
-  if (entry_block) stack.push_back(entry_block);
-
-  while (!stack.empty()) {
-    auto* block = stack.back();
-    stack.pop_back();
-
-    if (!seen.insert(block).second) continue;
-
-    auto* terminator = block->terminator();
-    if (terminator->opcode() == SpvOpUnreachable) {
-      return _.diag(SPV_ERROR_INVALID_CFG, block->label())
-             << "Statically reachable blocks cannot be terminated by "
-                "OpUnreachable";
-    }
-
-    for (auto* succ : *block->successors()) {
-      stack.push_back(succ);
-    }
-  }
-
-  return SPV_SUCCESS;
-}
-
 spv_result_t PerformCfgChecks(ValidationState_t& _) {
   for (auto& function : _.functions()) {
     // Check all referenced blocks are defined within a function
@@ -857,8 +827,6 @@
       }
     }
 
-    if (auto error = ValidateUnreachableBlocks(_, function)) return error;
-
     /// Structured control flow checks are only required for shader capabilities
     if (_.HasCapability(SpvCapabilityShader)) {
       if (auto error = StructuredControlFlowChecks(_, &function, back_edges))

test/val/val_cfg_test.cpp

diff --git a/test/val/val_cfg_test.cpp b/test/val/val_cfg_test.cpp
index 8f39a00..72bfa42 100644
--- a/test/val/val_cfg_test.cpp
+++ b/test/val/val_cfg_test.cpp
@@ -1203,11 +1203,7 @@
 TEST_P(ValidateCFG, UnreachableMergeWithBranchUse) {
   CompileSuccessfully(
       GetUnreachableMergeWithBranchUse(GetParam(), SPV_ENV_UNIVERSAL_1_0));
-  EXPECT_EQ(SPV_ERROR_INVALID_CFG, ValidateInstructions());
-  EXPECT_THAT(
-      getDiagnosticString(),
-      HasSubstr(
-          "Statically reachable blocks cannot be terminated by OpUnreachable"));
+  EXPECT_EQ(SPV_SUCCESS, ValidateInstructions());
 }
 
 TEST_F(ValidateCFG, WebGPUUnreachableMergeWithBranchUse) {
@@ -1942,10 +1938,7 @@
   str += "OpFunctionEnd";
 
   CompileSuccessfully(str);
-  EXPECT_EQ(SPV_ERROR_INVALID_CFG, ValidateInstructions());
-  EXPECT_THAT(getDiagnosticString(),
-              HasSubstr("Statically reachable blocks cannot be terminated by "
-                        "OpUnreachable"));
+  EXPECT_EQ(SPV_SUCCESS, ValidateInstructions());
 }
 
 TEST_F(ValidateCFG, LoopWithZeroBackEdgesBad) {
@@ -2873,11 +2866,7 @@
 )";
 
   CompileSuccessfully(text);
-  EXPECT_EQ(SPV_ERROR_INVALID_CFG, ValidateInstructions());
-  EXPECT_THAT(
-      getDiagnosticString(),
-      HasSubstr(
-          "Statically reachable blocks cannot be terminated by OpUnreachable"));
+  EXPECT_EQ(SPV_SUCCESS, ValidateInstructions());
 }
 
 TEST_F(ValidateCFG, ReachableOpUnreachableOpBranch) {
@@ -2896,11 +2885,7 @@
 )";
 
   CompileSuccessfully(text);
-  EXPECT_EQ(SPV_ERROR_INVALID_CFG, ValidateInstructions());
-  EXPECT_THAT(
-      getDiagnosticString(),
-      HasSubstr(
-          "Statically reachable blocks cannot be terminated by OpUnreachable"));
+  EXPECT_EQ(SPV_SUCCESS, ValidateInstructions());
 }
 
 TEST_F(ValidateCFG, ReachableOpUnreachableOpBranchConditional) {
@@ -2923,11 +2908,7 @@
 )";
 
   CompileSuccessfully(text);
-  EXPECT_EQ(SPV_ERROR_INVALID_CFG, ValidateInstructions());
-  EXPECT_THAT(
-      getDiagnosticString(),
-      HasSubstr(
-          "Statically reachable blocks cannot be terminated by OpUnreachable"));
+  EXPECT_EQ(SPV_SUCCESS, ValidateInstructions());
 }
 
 TEST_F(ValidateCFG, ReachableOpUnreachableOpSwitch) {
@@ -2952,11 +2933,7 @@
 )";
 
   CompileSuccessfully(text);
-  EXPECT_EQ(SPV_ERROR_INVALID_CFG, ValidateInstructions());
-  EXPECT_THAT(
-      getDiagnosticString(),
-      HasSubstr(
-          "Statically reachable blocks cannot be terminated by OpUnreachable"));
+  EXPECT_EQ(SPV_SUCCESS, ValidateInstructions());
 }
 
 TEST_F(ValidateCFG, ReachableOpUnreachableLoop) {
@@ -2980,11 +2957,7 @@
 )";
 
   CompileSuccessfully(text);
-  EXPECT_EQ(SPV_ERROR_INVALID_CFG, ValidateInstructions());
-  EXPECT_THAT(
-      getDiagnosticString(),
-      HasSubstr(
-          "Statically reachable blocks cannot be terminated by OpUnreachable"));
+  EXPECT_EQ(SPV_SUCCESS, ValidateInstructions());
 }
 
 TEST_F(ValidateCFG, UnreachableLoopBadBackedge) {