[llvm] [GlobalISel] Add Knownbits for G_LOAD/ZEXTLOAD/SEXTLOAD with range metadata (PR #86431)

[via llvm-commits]

llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-llvm-globalisel

Author: David Green (davemgreen)

<details>
<summary>Changes</summary>

Similar to #<!-- -->80829 for GlobalISel.

---
Full diff: https://github.com/llvm/llvm-project/pull/86431.diff


3 Files Affected:

- (modified) llvm/lib/CodeGen/GlobalISel/GISelKnownBits.cpp (+12-7) 
- (modified) llvm/unittests/CodeGen/GlobalISel/KnownBitsTest.cpp (+80-14) 
- (modified) llvm/unittests/CodeGen/GlobalISel/KnownBitsVectorTest.cpp (+1-1) 


``````````diff
diff --git a/llvm/lib/CodeGen/GlobalISel/GISelKnownBits.cpp b/llvm/lib/CodeGen/GlobalISel/GISelKnownBits.cpp
index 2e2cc9a95bd95c..101676510fab83 100644
--- a/llvm/lib/CodeGen/GlobalISel/GISelKnownBits.cpp
+++ b/llvm/lib/CodeGen/GlobalISel/GISelKnownBits.cpp
@@ -405,18 +405,23 @@ void GISelKnownBits::computeKnownBitsImpl(Register R, KnownBits &Known,
   }
   case TargetOpcode::G_LOAD: {
     const MachineMemOperand *MMO = *MI.memoperands_begin();
-    if (const MDNode *Ranges = MMO->getRanges()) {
-      computeKnownBitsFromRangeMetadata(*Ranges, Known);
-    }
-
+    KnownBits KnownRange(MMO->getMemoryType().getScalarSizeInBits());
+    if (const MDNode *Ranges = MMO->getRanges())
+      computeKnownBitsFromRangeMetadata(*Ranges, KnownRange);
+    Known = KnownRange.anyext(Known.getBitWidth());
     break;
   }
+  case TargetOpcode::G_SEXTLOAD:
   case TargetOpcode::G_ZEXTLOAD: {
     if (DstTy.isVector())
       break;
-    // Everything above the retrieved bits is zero
-    Known.Zero.setBitsFrom(
-        (*MI.memoperands_begin())->getSizeInBits().getValue());
+    const MachineMemOperand *MMO = *MI.memoperands_begin();
+    KnownBits KnownRange(MMO->getMemoryType().getScalarSizeInBits());
+    if (const MDNode *Ranges = MMO->getRanges())
+      computeKnownBitsFromRangeMetadata(*Ranges, KnownRange);
+    Known = Opcode == TargetOpcode::G_SEXTLOAD
+                ? KnownRange.sext(Known.getBitWidth())
+                : KnownRange.zext(Known.getBitWidth());
     break;
   }
   case TargetOpcode::G_ASHR: {
diff --git a/llvm/unittests/CodeGen/GlobalISel/KnownBitsTest.cpp b/llvm/unittests/CodeGen/GlobalISel/KnownBitsTest.cpp
index f3659bc6956361..ef80eed8d18023 100644
--- a/llvm/unittests/CodeGen/GlobalISel/KnownBitsTest.cpp
+++ b/llvm/unittests/CodeGen/GlobalISel/KnownBitsTest.cpp
@@ -1100,6 +1100,25 @@ TEST_F(AMDGPUGISelMITest, TestIsKnownToBeAPowerOfTwo) {
   EXPECT_TRUE(isKnownToBeAPowerOfTwo(CopyOrPow2, *MRI, &KB));
 }
 
+static void AddRangeMetadata(LLVMContext &Context, MachineInstr *Load) {
+  IntegerType *Int8Ty = Type::getInt8Ty(Context);
+
+  // Value must be in [0, 2)
+  Metadata *LowAndHigh[] = {
+      ConstantAsMetadata::get(ConstantInt::get(Int8Ty, 0)),
+      ConstantAsMetadata::get(ConstantInt::get(Int8Ty, 2))};
+  auto NewMDNode = MDNode::get(Context, LowAndHigh);
+  const MachineMemOperand *OldMMO = *Load->memoperands_begin();
+  MachineMemOperand *NewMMO =
+      Load->getParent()->getParent()->getMachineMemOperand(
+          OldMMO->getPointerInfo(), OldMMO->getFlags(), OldMMO->getMemoryType(),
+          OldMMO->getAlign(), OldMMO->getAAInfo(), NewMDNode);
+  MachineIRBuilder MIB(*Load);
+  MIB.buildLoadInstr(Load->getOpcode(), Load->getOperand(0),
+                     Load->getOperand(1), *NewMMO);
+  Load->eraseFromParent();
+}
+
 TEST_F(AArch64GISelMITest, TestMetadata) {
   StringRef MIRString = "  %imp:_(p0) = G_IMPLICIT_DEF\n"
                         "  %load:_(s8) = G_LOAD %imp(p0) :: (load (s8))\n"
@@ -1120,20 +1139,7 @@ TEST_F(AArch64GISelMITest, TestMetadata) {
   MachineInstr *And = MRI->getVRegDef(SrcReg);
   MachineInstr *Ext = MRI->getVRegDef(And->getOperand(1).getReg());
   MachineInstr *Load = MRI->getVRegDef(Ext->getOperand(1).getReg());
-  IntegerType *Int8Ty = Type::getInt8Ty(Context);
-
-  // Value must be in [0, 2)
-  Metadata *LowAndHigh[] = {
-      ConstantAsMetadata::get(ConstantInt::get(Int8Ty, 0)),
-      ConstantAsMetadata::get(ConstantInt::get(Int8Ty, 2))};
-  auto NewMDNode = MDNode::get(Context, LowAndHigh);
-  const MachineMemOperand *OldMMO = *Load->memoperands_begin();
-  MachineMemOperand NewMMO(OldMMO->getPointerInfo(), OldMMO->getFlags(),
-                           OldMMO->getSizeInBits(), OldMMO->getAlign(),
-                           OldMMO->getAAInfo(), NewMDNode);
-  MachineIRBuilder MIB(*Load);
-  MIB.buildLoad(Load->getOperand(0), Load->getOperand(1), NewMMO);
-  Load->eraseFromParent();
+  AddRangeMetadata(Context, Load);
 
   GISelKnownBits Info(*MF);
   KnownBits Res = Info.getKnownBits(And->getOperand(1).getReg());
@@ -1148,6 +1154,66 @@ TEST_F(AArch64GISelMITest, TestMetadata) {
   EXPECT_EQ(Mask.getZExtValue(), Res.Zero.getZExtValue());
 }
 
+TEST_F(AArch64GISelMITest, TestMetadataExt) {
+  StringRef MIRString = "  %imp:_(p0) = G_IMPLICIT_DEF\n"
+                        "  %load:_(s32) = G_LOAD %imp(p0) :: (load (s8))\n"
+                        "  %copy:_(s32) = COPY %load(s32)\n";
+  setUp(MIRString);
+  if (!TM)
+    GTEST_SKIP();
+
+  Register CopyReg = Copies[Copies.size() - 1];
+  MachineInstr *FinalCopy = MRI->getVRegDef(CopyReg);
+  Register SrcReg = FinalCopy->getOperand(1).getReg();
+  MachineInstr *Load = MRI->getVRegDef(SrcReg);
+  AddRangeMetadata(Context, Load);
+
+  GISelKnownBits Info(*MF);
+  KnownBits Res = Info.getKnownBits(SrcReg);
+  EXPECT_TRUE(Res.One.isZero());
+  EXPECT_EQ(Res.Zero.getZExtValue(), 0xfeu);
+}
+
+TEST_F(AArch64GISelMITest, TestMetadataZExt) {
+  StringRef MIRString = "  %imp:_(p0) = G_IMPLICIT_DEF\n"
+                        "  %load:_(s32) = G_ZEXTLOAD %imp(p0) :: (load (s8))\n"
+                        "  %copy:_(s32) = COPY %load(s32)\n";
+  setUp(MIRString);
+  if (!TM)
+    GTEST_SKIP();
+
+  Register CopyReg = Copies[Copies.size() - 1];
+  MachineInstr *FinalCopy = MRI->getVRegDef(CopyReg);
+  Register SrcReg = FinalCopy->getOperand(1).getReg();
+  MachineInstr *Load = MRI->getVRegDef(SrcReg);
+  AddRangeMetadata(Context, Load);
+
+  GISelKnownBits Info(*MF);
+  KnownBits Res = Info.getKnownBits(SrcReg);
+  EXPECT_TRUE(Res.One.isZero());
+  EXPECT_EQ(Res.Zero.getZExtValue(), 0xfffffffe);
+}
+
+TEST_F(AArch64GISelMITest, TestMetadataSExt) {
+  StringRef MIRString = "  %imp:_(p0) = G_IMPLICIT_DEF\n"
+                        "  %load:_(s32) = G_SEXTLOAD %imp(p0) :: (load (s8))\n"
+                        "  %copy:_(s32) = COPY %load(s32)\n";
+  setUp(MIRString);
+  if (!TM)
+    GTEST_SKIP();
+
+  Register CopyReg = Copies[Copies.size() - 1];
+  MachineInstr *FinalCopy = MRI->getVRegDef(CopyReg);
+  Register SrcReg = FinalCopy->getOperand(1).getReg();
+  MachineInstr *Load = MRI->getVRegDef(SrcReg);
+  AddRangeMetadata(Context, Load);
+
+  GISelKnownBits Info(*MF);
+  KnownBits Res = Info.getKnownBits(SrcReg);
+  EXPECT_TRUE(Res.One.isZero());
+  EXPECT_EQ(Res.Zero.getZExtValue(), 0xfffffffe);
+}
+
 TEST_F(AArch64GISelMITest, TestKnownBitsExt) {
   StringRef MIRString = "  %c1:_(s16) = G_CONSTANT i16 1\n"
                         "  %x:_(s16) = G_IMPLICIT_DEF\n"
diff --git a/llvm/unittests/CodeGen/GlobalISel/KnownBitsVectorTest.cpp b/llvm/unittests/CodeGen/GlobalISel/KnownBitsVectorTest.cpp
index ab180cd1cc2726..dd6edd35a8468b 100644
--- a/llvm/unittests/CodeGen/GlobalISel/KnownBitsVectorTest.cpp
+++ b/llvm/unittests/CodeGen/GlobalISel/KnownBitsVectorTest.cpp
@@ -1008,7 +1008,7 @@ TEST_F(AArch64GISelMITest, TestVectorMetadata) {
   auto *NewMDNode = MDNode::get(Context, LowAndHigh);
   const MachineMemOperand *OldMMO = *Load->memoperands_begin();
   MachineMemOperand NewMMO(OldMMO->getPointerInfo(), OldMMO->getFlags(),
-                           OldMMO->getSizeInBits(), OldMMO->getAlign(),
+                           OldMMO->getMemoryType(), OldMMO->getAlign(),
                            OldMMO->getAAInfo(), NewMDNode);
   MachineIRBuilder MIB(*Load);
   MIB.buildLoad(Load->getOperand(0), Load->getOperand(1), NewMMO);

``````````

</details>


https://github.com/llvm/llvm-project/pull/86431