Add CodeGenTarget::guessInstructionProperties.

Currently, TableGen just guesses instruction properties when it can't
infer them form patterns.

This adds a guessInstructionProperties flag to the instruction set
definition that will be used to disable guessing. The flag is intended
as a migration aid. It will be removed again when no more targets need
their properties guessed.

llvm-svn: 162460

include/llvm/Target/Target.td

@@ -631,6 +631,17 @@ class InstrInfo {
   // Sparc manual specifies its instructions in the format [31..0] (big), while
   // PowerPC specifies them using the format [0..31] (little).
   bit isLittleEndianEncoding = 0;
+
+  // The instruction properties mayLoad, mayStore, and hasSideEffects are unset
+  // by default, and TableGen will infer their value from the instruction
+  // pattern when possible.
+  //
+  // Normally, TableGen will issue an error it it can't infer the value of a
+  // property that hasn't been set explicitly. When guessInstructionProperties
+  // is set, it will guess a safe value instead.
+  //
+  // This option is a temporary migration help. It will go away.
+  bit guessInstructionProperties = 1;
 }
 
 // Standard Pseudo Instructions.

utils/TableGen/CodeGenTarget.cpp

@@ -334,6 +334,15 @@ bool CodeGenTarget::isLittleEndianEncoding() const {
   return getInstructionSet()->getValueAsBit("isLittleEndianEncoding");
 }
 
+/// guessInstructionProperties - Return true if it's OK to guess instruction
+/// properties instead of raising an error.
+///
+/// This is configurable as a temporary migration aid. It will eventually be
+/// permanently false.
+bool CodeGenTarget::guessInstructionProperties() const {
+  return getInstructionSet()->getValueAsBit("guessInstructionProperties");
+}
+
 //===----------------------------------------------------------------------===//
 // ComplexPattern implementation
 //

utils/TableGen/CodeGenTarget.h

@@ -177,6 +177,10 @@ public:
   ///
   bool isLittleEndianEncoding() const;
 
+  /// guessInstructionProperties - should we just guess unset instruction
+  /// properties?
+  bool guessInstructionProperties() const;
+
 private:
   void ComputeInstrsByEnum() const;
 };