AArch64/GlobalISel: Narrow stack passed argument access size

[arsenm]

Summary

This fixes a verifier error in the testcase from bug 47619.

The stack passed s3 value was widened to 4-bytes, and producing a
4-byte memory access with a < 1 byte result type. We need to either
widen the result type or narrow the access size. This copies the code
directly from the AMDGPU handling, which narrows the load size. I
don't like that every target has to handle this, but this is currently
broken on the 11 release branch and this is the simplest fix.

This reverts commit 42bfa7c63b85e76fe16521d1671afcafaf8f64ed.

[aemerson]

LGTM.

[arsenm]

6cb0d23f2ea6fb25106b0380797ccbc2141d71e1

llvm/lib/Target/AArch64/GISel/AArch64CallLowering.cpp

void assignValueToReg(Register ValVReg, Register PhysReg,
     case CCValAssign::LocInfo::AExt: {
       auto Copy = MIRBuilder.buildCopy(LLT{VA.getLocVT()}, PhysReg);
       MIRBuilder.buildTrunc(ValVReg, Copy);
       break;
     }
     }
   }
 
-  void assignValueToAddress(Register ValVReg, Register Addr, uint64_t Size,
+  void assignValueToAddress(Register ValVReg, Register Addr, uint64_t MemSize,
                             MachinePointerInfo &MPO, CCValAssign &VA) override {
     MachineFunction &MF = MIRBuilder.getMF();
+
+    // The reported memory location may be wider than the value.
+    const LLT RegTy = MRI.getType(ValVReg);
+    MemSize = std::min(static_cast<uint64_t>(RegTy.getSizeInBytes()), MemSize);
+
     auto MMO = MF.getMachineMemOperand(
-        MPO, MachineMemOperand::MOLoad | MachineMemOperand::MOInvariant, Size,
+        MPO, MachineMemOperand::MOLoad | MachineMemOperand::MOInvariant, MemSize,
         inferAlignFromPtrInfo(MF, MPO));
     MIRBuilder.buildLoad(ValVReg, Addr, *MMO);
   }
 
   /// How the physical register gets marked varies between formal
   /// parameters (it's a basic-block live-in), and a call instruction
   /// (it's an implicit-def of the BL).
   virtual void markPhysRegUsed(MCRegister PhysReg) = 0;

llvm/test/CodeGen/AArch64/GlobalISel/irtranslator-stack-evt-bug47619.ll

+; NOTE: Assertions have been autogenerated by utils/update_mir_test_checks.py
+; RUN: llc -global-isel -mtriple=aarch64-unknown-unknown -stop-after=irtranslator -verify-machineinstrs %s -o - | FileCheck %s
+
+; Make sure the i3 %arg8 value is correctly handled. This was trying
+; to use MVT for EVT values passed on the stack and asserting before
+; b98f902f1877c3d679f77645a267edc89ffcd5d6
+define i3 @bug47619(i64 %arg, i64 %arg1, i64 %arg2, i64 %arg3, i64 %arg4, i64 %arg5, i64 %arg6, i64 %arg7, i3 %arg8) {
+  ; CHECK-LABEL: name: bug47619
+  ; CHECK: bb.1.bb:
+  ; CHECK:   liveins: $x0, $x1, $x2, $x3, $x4, $x5, $x6, $x7
+  ; CHECK:   [[COPY:%[0-9]+]]:_(s64) = COPY $x0
+  ; CHECK:   [[COPY1:%[0-9]+]]:_(s64) = COPY $x1
+  ; CHECK:   [[COPY2:%[0-9]+]]:_(s64) = COPY $x2
+  ; CHECK:   [[COPY3:%[0-9]+]]:_(s64) = COPY $x3
+  ; CHECK:   [[COPY4:%[0-9]+]]:_(s64) = COPY $x4
+  ; CHECK:   [[COPY5:%[0-9]+]]:_(s64) = COPY $x5
+  ; CHECK:   [[COPY6:%[0-9]+]]:_(s64) = COPY $x6
+  ; CHECK:   [[COPY7:%[0-9]+]]:_(s64) = COPY $x7
+  ; CHECK:   [[FRAME_INDEX:%[0-9]+]]:_(p0) = G_FRAME_INDEX %fixed-stack.0
+  ; CHECK:   [[LOAD:%[0-9]+]]:_(s3) = G_LOAD [[FRAME_INDEX]](p0) :: (invariant load 1 from %fixed-stack.0, align 16)
+  ; CHECK:   [[ANYEXT:%[0-9]+]]:_(s32) = G_ANYEXT [[LOAD]](s3)
+  ; CHECK:   $w0 = COPY [[ANYEXT]](s32)
+  ; CHECK:   RET_ReallyLR implicit $w0
+bb:
+  ret i3 %arg8
+}