[PATCH] D91754: [GlobalISel] Add isConstFalseVal helper to Utils

[Jessica Paquette via Phabricator via llvm-commits]

paquette created this revision.
paquette added reviewers: arsenm, aemerson.
Herald added subscribers: hiraditya, rovka.
Herald added a project: LLVM.
paquette requested review of this revision.
Herald added a subscriber: wdng.

Add a utility function which returns true if the given value is a constant false value.

This is necessary to port one of the compare simplifications in `TargetLowering::SimplifySetCC`.


https://reviews.llvm.org/D91754

Files:
  llvm/include/llvm/CodeGen/GlobalISel/Utils.h
  llvm/lib/CodeGen/GlobalISel/Utils.cpp
  llvm/unittests/CodeGen/GlobalISel/GISelUtilsTest.cpp


Index: llvm/unittests/CodeGen/GlobalISel/GISelUtilsTest.cpp
===================================================================
--- llvm/unittests/CodeGen/GlobalISel/GISelUtilsTest.cpp
+++ llvm/unittests/CodeGen/GlobalISel/GISelUtilsTest.cpp
@@ -294,4 +294,24 @@
   }
 }
 
+TEST_F(AArch64GISelMITest, ConstFalseTest) {
+  setUp();
+  if (!TM)
+    return;
+  const auto &TLI = *B.getMF().getSubtarget().getTargetLowering();
+  bool BooleanChoices[2] = {true, false};
+
+  // AArch64 uses ZeroOrOneBooleanContent for scalars, and
+  // ZeroOrNegativeOneBooleanContent for vectors.
+  for (auto IsVec : BooleanChoices) {
+    for (auto IsFP : BooleanChoices) {
+      EXPECT_TRUE(isConstFalseVal(TLI, 0, IsVec, IsFP));
+      EXPECT_FALSE(isConstFalseVal(TLI, 1, IsVec, IsFP));
+
+      // This would be true with UndefinedBooleanContent.
+      EXPECT_FALSE(isConstFalseVal(TLI, 2, IsVec, IsFP));
+    }
+  }
+}
+
 } // namespace
Index: llvm/lib/CodeGen/GlobalISel/Utils.cpp
===================================================================
--- llvm/lib/CodeGen/GlobalISel/Utils.cpp
+++ llvm/lib/CodeGen/GlobalISel/Utils.cpp
@@ -734,6 +734,18 @@
   llvm_unreachable("Invalid boolean contents");
 }
 
+bool llvm::isConstFalseVal(const TargetLowering &TLI, int64_t Val,
+                           bool IsVector, bool IsFP) {
+  switch (TLI.getBooleanContents(IsVector, IsFP)) {
+  case TargetLowering::UndefinedBooleanContent:
+    return ~Val & 0x1;
+  case TargetLowering::ZeroOrOneBooleanContent:
+  case TargetLowering::ZeroOrNegativeOneBooleanContent:
+    return Val == 0;
+  }
+  llvm_unreachable("Invalid boolean contents");
+}
+
 bool llvm::isExtendedTrueVal(const TargetLowering &TLI, int64_t Val,
                              const LLT &ExtTy, const LLT &OrigTy, bool IsFP,
                              bool IsSignExtended) {
Index: llvm/include/llvm/CodeGen/GlobalISel/Utils.h
===================================================================
--- llvm/include/llvm/CodeGen/GlobalISel/Utils.h
+++ llvm/include/llvm/CodeGen/GlobalISel/Utils.h
@@ -258,6 +258,11 @@
 bool isConstTrueVal(const TargetLowering &TLI, int64_t Val, bool IsVector,
                     bool IsFP);
 
+/// Returns true if given the TargetLowering's boolean contents information,
+/// the value \p Val contains a false value.
+bool isConstFalseVal(const TargetLowering &TLI, int64_t Val, bool IsVector,
+                     bool IsFP);
+
 /// \returns true if \p Val is a true value extended from \p OrigTy to \p ExtTy.
 /// \p IsFP is true if the value is floating point.
 /// \p IsSignExtended is true if the extension should be signed.


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