[llvm] 95605b7 - AMDGPU/GlobalISel: Implement computeKnownAlignForTargetInstr

[Matt Arsenault via llvm-commits]

Author: Matt Arsenault
Date: 2020-06-18T17:28:00-04:00
New Revision: 95605b784b350b9c51fd4f15f312b50566cab30d

URL: https://github.com/llvm/llvm-project/commit/95605b784b350b9c51fd4f15f312b50566cab30d
DIFF: https://github.com/llvm/llvm-project/commit/95605b784b350b9c51fd4f15f312b50566cab30d.diff

LOG: AMDGPU/GlobalISel: Implement computeKnownAlignForTargetInstr

We probably need to move where intrinsics are lowered to copies to
make this useful.

Added: 
    

Modified: 
    llvm/lib/CodeGen/GlobalISel/GISelKnownBits.cpp
    llvm/lib/Target/AMDGPU/SIISelLowering.cpp
    llvm/lib/Target/AMDGPU/SIISelLowering.h
    llvm/unittests/CodeGen/GlobalISel/KnownBitsTest.cpp

Removed: 
    


################################################################################
diff  --git a/llvm/lib/CodeGen/GlobalISel/GISelKnownBits.cpp b/llvm/lib/CodeGen/GlobalISel/GISelKnownBits.cpp
index 3a4a373a6c73..e5d77b0eb857 100644
--- a/llvm/lib/CodeGen/GlobalISel/GISelKnownBits.cpp
+++ b/llvm/lib/CodeGen/GlobalISel/GISelKnownBits.cpp
@@ -34,6 +34,8 @@ GISelKnownBits::GISelKnownBits(MachineFunction &MF, unsigned MaxDepth)
 Align GISelKnownBits::computeKnownAlignment(Register R, unsigned Depth) {
   const MachineInstr *MI = MRI.getVRegDef(R);
   switch (MI->getOpcode()) {
+  case TargetOpcode::COPY:
+    return computeKnownAlignment(MI->getOperand(1).getReg(), Depth);
   case TargetOpcode::G_FRAME_INDEX: {
     int FrameIdx = MI->getOperand(1).getIndex();
     return MF.getFrameInfo().getObjectAlign(FrameIdx);

diff  --git a/llvm/lib/Target/AMDGPU/SIISelLowering.cpp b/llvm/lib/Target/AMDGPU/SIISelLowering.cpp
index 2fc55fd5b280..e7cc5afdef9b 100644
--- a/llvm/lib/Target/AMDGPU/SIISelLowering.cpp
+++ b/llvm/lib/Target/AMDGPU/SIISelLowering.cpp
@@ -35,6 +35,7 @@
 #include "llvm/CodeGen/CallingConvLower.h"
 #include "llvm/CodeGen/DAGCombine.h"
 #include "llvm/CodeGen/ISDOpcodes.h"
+#include "llvm/CodeGen/GlobalISel/GISelKnownBits.h"
 #include "llvm/CodeGen/MachineBasicBlock.h"
 #include "llvm/CodeGen/MachineFrameInfo.h"
 #include "llvm/CodeGen/MachineFunction.h"
@@ -11292,6 +11293,27 @@ void SITargetLowering::computeKnownBitsForFrameIndex(
   Known.Zero.setHighBits(getSubtarget()->getKnownHighZeroBitsForFrameIndex());
 }
 
+Align SITargetLowering::computeKnownAlignForTargetInstr(
+  GISelKnownBits &KB, Register R, const MachineRegisterInfo &MRI,
+  unsigned Depth) const {
+  const MachineInstr *MI = MRI.getVRegDef(R);
+  switch (MI->getOpcode()) {
+  case AMDGPU::G_INTRINSIC:
+  case AMDGPU::G_INTRINSIC_W_SIDE_EFFECTS: {
+    // FIXME: Can this move to generic code? What about the case where the call
+    // site specifies a lower alignment?
+    Intrinsic::ID IID = MI->getIntrinsicID();
+    LLVMContext &Ctx = KB.getMachineFunction().getFunction().getContext();
+    AttributeList Attrs = Intrinsic::getAttributes(Ctx, IID);
+    if (MaybeAlign RetAlign = Attrs.getRetAlignment())
+      return *RetAlign;
+    return Align(1);
+  }
+  default:
+    return Align(1);
+  }
+}
+
 Align SITargetLowering::getPrefLoopAlignment(MachineLoop *ML) const {
   const Align PrefAlign = TargetLowering::getPrefLoopAlignment(ML);
   const Align CacheLineAlign = Align(64);

diff  --git a/llvm/lib/Target/AMDGPU/SIISelLowering.h b/llvm/lib/Target/AMDGPU/SIISelLowering.h
index 2dae7d9b5729..3365c08b9e76 100644
--- a/llvm/lib/Target/AMDGPU/SIISelLowering.h
+++ b/llvm/lib/Target/AMDGPU/SIISelLowering.h
@@ -408,6 +408,9 @@ class SITargetLowering final : public AMDGPUTargetLowering {
                                      KnownBits &Known,
                                      const MachineFunction &MF) const override;
 
+  Align computeKnownAlignForTargetInstr(GISelKnownBits &Analysis, Register R,
+                                        const MachineRegisterInfo &MRI,
+                                        unsigned Depth = 0) const override;
   bool isSDNodeSourceOfDivergence(const SDNode *N,
     FunctionLoweringInfo *FLI, LegacyDivergenceAnalysis *DA) const override;
 

diff  --git a/llvm/unittests/CodeGen/GlobalISel/KnownBitsTest.cpp b/llvm/unittests/CodeGen/GlobalISel/KnownBitsTest.cpp
index fe0c14270ecf..329c8040158d 100644
--- a/llvm/unittests/CodeGen/GlobalISel/KnownBitsTest.cpp
+++ b/llvm/unittests/CodeGen/GlobalISel/KnownBitsTest.cpp
@@ -431,3 +431,35 @@ TEST_F(AMDGPUGISelMITest, TestNumSignBitsTrunc) {
   EXPECT_EQ(16u, Info.computeNumSignBits(CopyLoadUShort));
   EXPECT_EQ(17u, Info.computeNumSignBits(CopyLoadSShort));
 }
+
+TEST_F(AMDGPUGISelMITest, TestTargetKnownAlign) {
+  StringRef MIRString =
+    "  %5:_(p4) = G_INTRINSIC intrinsic(@llvm.amdgcn.dispatch.ptr)\n"
+    "  %6:_(p4) = COPY %5\n"
+    "  %7:_(p4) = G_INTRINSIC intrinsic(@llvm.amdgcn.queue.ptr)\n"
+    "  %8:_(p4) = COPY %7\n"
+    "  %9:_(p4) = G_INTRINSIC intrinsic(@llvm.amdgcn.kernarg.segment.ptr)\n"
+    "  %10:_(p4) = COPY %9\n"
+    "  %11:_(p4) = G_INTRINSIC intrinsic(@llvm.amdgcn.implicitarg.ptr)\n"
+    "  %12:_(p4) = COPY %11\n"
+    "  %13:_(p4) = G_INTRINSIC intrinsic(@llvm.amdgcn.implicit.buffer.ptr)\n"
+    "  %14:_(p4) = COPY %13\n";
+
+  setUp(MIRString);
+  if (!TM)
+    return;
+
+  Register CopyDispatchPtr = Copies[Copies.size() - 5];
+  Register CopyQueuePtr = Copies[Copies.size() - 4];
+  Register CopyKernargSegmentPtr = Copies[Copies.size() - 3];
+  Register CopyImplicitArgPtr = Copies[Copies.size() - 2];
+  Register CopyImplicitBufferPtr = Copies[Copies.size() - 1];
+
+  GISelKnownBits Info(*MF);
+
+  EXPECT_EQ(Align(4), Info.computeKnownAlignment(CopyDispatchPtr));
+  EXPECT_EQ(Align(4), Info.computeKnownAlignment(CopyQueuePtr));
+  EXPECT_EQ(Align(4), Info.computeKnownAlignment(CopyKernargSegmentPtr));
+  EXPECT_EQ(Align(4), Info.computeKnownAlignment(CopyImplicitArgPtr));
+  EXPECT_EQ(Align(4), Info.computeKnownAlignment(CopyImplicitBufferPtr));
+}