Start inferring side effect information more aggressively, and fix many bugs in the

x86 backend where instructions were not marked maystore/mayload, and perf issues where
instructions were not marked neverHasSideEffects.  It would be really nice if we could
write patterns for copy instructions.

I have audited all the x86 instructions down to MOVDQAmr.  The flags on others and on
other targets are probably not right in all cases, but no clients currently use this
info that are enabled by default.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@45829 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 33 insertions, 22 deletions

diff --git a/utils/TableGen/InstrInfoEmitter.cpp b/utils/TableGen/InstrInfoEmitter.cpp
index bcb8be6625..ed48c33004 100644
--- a/utils/TableGen/InstrInfoEmitter.cpp
+++ b/utils/TableGen/InstrInfoEmitter.cpp
@@ -152,22 +152,36 @@ public:
     : CDP(cdp), mayStore(maystore), mayLoad(mayload), HasSideEffects(hse){
   }
   
-  void Analyze(Record *InstRecord) {
+  /// Analyze - Analyze the specified instruction, returning true if the
+  /// instruction had a pattern.
+  bool Analyze(Record *InstRecord) {
     const TreePattern *Pattern = CDP.getInstruction(InstRecord).getPattern();
     if (Pattern == 0) {
       HasSideEffects = 1;
-      return;  // No pattern.
+      return false;  // No pattern.
     }
     
     // FIXME: Assume only the first tree is the pattern. The others are clobber
     // nodes.
     AnalyzeNode(Pattern->getTree(0));
+    return true;
   }
   
 private:
   void AnalyzeNode(const TreePatternNode *N) {
-    if (N->isLeaf())
+    if (N->isLeaf()) {
+      if (DefInit *DI = dynamic_cast<DefInit*>(N->getLeafValue())) {
+        Record *LeafRec = DI->getDef();
+        // Handle ComplexPattern leaves.
+        if (LeafRec->isSubClassOf("ComplexPattern")) {
+          const ComplexPattern &CP = CDP.getComplexPattern(LeafRec);
+          if (CP.hasProperty(SDNPMayStore)) mayStore = true;
+          if (CP.hasProperty(SDNPMayLoad)) mayLoad = true;
+          if (CP.hasProperty(SDNPSideEffect)) HasSideEffects = true;
+        }
+      }
       return;
+    }
 
     // Analyze children.
     for (unsigned i = 0, e = N->getNumChildren(); i != e; ++i)
@@ -180,17 +194,10 @@ private:
     // Get information about the SDNode for the operator.
     const SDNodeInfo &OpInfo = CDP.getSDNodeInfo(N->getOperator());
     
-    // If node writes to memory, it obviously stores to memory.
-    if (OpInfo.hasProperty(SDNPMayStore))
-      mayStore = true;
-    
-    // If it reads memory, remember this.
-    if (OpInfo.hasProperty(SDNPMayLoad))
-      mayLoad = true;
-
-    // If it reads memory, remember this.
-    if (OpInfo.hasProperty(SDNPSideEffect))
-      HasSideEffects = true;
+    // Notice properties of the node.
+    if (OpInfo.hasProperty(SDNPMayStore)) mayStore = true;
+    if (OpInfo.hasProperty(SDNPMayLoad)) mayLoad = true;
+    if (OpInfo.hasProperty(SDNPSideEffect)) HasSideEffects = true;
     
     if (const CodeGenIntrinsic *IntInfo = N->getIntrinsicInfo(CDP)) {
       // If this is an intrinsic, analyze it.
@@ -213,7 +220,8 @@ void InstrInfoEmitter::InferFromPattern(const CodeGenInstruction &Inst,
                                         bool &HasSideEffects) {
   MayStore = MayLoad = HasSideEffects = false;
   
-  InstAnalyzer(CDP, MayStore, MayLoad, HasSideEffects).Analyze(Inst.TheDef);
+  bool HadPattern =
+    InstAnalyzer(CDP, MayStore, MayLoad, HasSideEffects).Analyze(Inst.TheDef);
 
   // InstAnalyzer only correctly analyzes mayStore/mayLoad so far.
   if (Inst.mayStore) {  // If the .td file explicitly sets mayStore, use it.
@@ -239,15 +247,18 @@ void InstrInfoEmitter::InferFromPattern(const CodeGenInstruction &Inst,
   }
   
   if (Inst.neverHasSideEffects) {
-    // If we already decided that this instruction has no side effects, then the
-    // .td file entry is redundant.
-    if (!HasSideEffects)
-      fprintf(stderr, 
-              "Warning: neverHasSideEffects flag explicitly set on instruction"
-              " '%s' but flag already inferred from pattern.\n", 
-              Inst.TheDef->getName().c_str());
+    if (HadPattern)
+      fprintf(stderr, "Warning: neverHasSideEffects set on instruction '%s' "
+              "which already has a pattern\n", Inst.TheDef->getName().c_str());
     HasSideEffects = false;
   }
+  
+  if (Inst.hasSideEffects) {
+    if (HasSideEffects)
+      fprintf(stderr, "Warning: hasSideEffects set on instruction '%s' "
+              "which already inferred this.\n", Inst.TheDef->getName().c_str());
+    HasSideEffects = true;
+  }
 }