[SelectionDAGBuilder][RISCV] Fix crash when using a memory constraint with scalable vector type.

[topperc]

We need to use the minimum size of the scalable type and the correct stack ID.

The code in the PR is still invalid because the instruction used doesn't have a pointer operand. This is diagnosed later when the assembler parses it.

Fixes #99782

[llvmbot]

@llvm/pr-subscribers-llvm-selectiondag

Author: Craig Topper (topperc)

Changes

… with scalable vector type.

We need to use the minimum size of the scalable type and the correct stack ID.

The code in the PR is still invalid because the instruction used doesn't have a pointer operand. This is diagnosed later when the assembler parses it.

---

Full diff: https://github.com/llvm/llvm-project/pull/99821.diff

2 Files Affected:

• (modified) llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp (+8-3)
• (added) llvm/test/CodeGen/RISCV/rvv/pr99782.ll (+18)

diff --git a/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp b/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
index 98a795edb7a03..37b1131d2f8a3 100644
--- a/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
@@ -9566,10 +9566,15 @@ static SDValue getAddressForMemoryInput(SDValue Chain, const SDLoc &Location,
   // Otherwise, create a stack slot and emit a store to it before the asm.
   Type *Ty = OpVal->getType();
   auto &DL = DAG.getDataLayout();
-  uint64_t TySize = DL.getTypeAllocSize(Ty);
+  TypeSize TySize = DL.getTypeAllocSize(Ty);
   MachineFunction &MF = DAG.getMachineFunction();
-  int SSFI = MF.getFrameInfo().CreateStackObject(
-      TySize, DL.getPrefTypeAlign(Ty), false);
+  const TargetFrameLowering *TFI = MF.getSubtarget().getFrameLowering();
+  int StackID = 0;
+  if (TySize.isScalable())
+    StackID = TFI->getStackIDForScalableVectors();
+  int SSFI = MF.getFrameInfo().CreateStackObject(TySize.getKnownMinValue(),
+                                                 DL.getPrefTypeAlign(Ty), false,
+                                                 nullptr, StackID);
   SDValue StackSlot = DAG.getFrameIndex(SSFI, TLI.getFrameIndexTy(DL));
   Chain = DAG.getTruncStore(Chain, Location, OpInfo.CallOperand, StackSlot,
                             MachinePointerInfo::getFixedStack(MF, SSFI),
diff --git a/llvm/test/CodeGen/RISCV/rvv/pr99782.ll b/llvm/test/CodeGen/RISCV/rvv/pr99782.ll
new file mode 100644
index 0000000000000..92c40f41f02b5
--- /dev/null
+++ b/llvm/test/CodeGen/RISCV/rvv/pr99782.ll
@@ -0,0 +1,18 @@
+; NOTE: Assertions have been autogenerated by utils/update_mir_test_checks.py UTC_ARGS: --version 5
+; RUN: llc < %s -mtriple=riscv64 -mattr=+v -stop-after=finalize-isel | FileCheck %s
+
+define void @vslidedown() {
+  ; CHECK-LABEL: name: vslidedown
+  ; CHECK: bb.0.entry:
+  ; CHECK-NEXT:   [[ADDI:%[0-9]+]]:gpr = ADDI %stack.0.v, 0
+  ; CHECK-NEXT:   [[VL8RE8_V:%[0-9]+]]:vrm8 = VL8RE8_V killed [[ADDI]] :: (load (<vscale x 1 x s512>) from %ir.v, align 1)
+  ; CHECK-NEXT:   [[ADDI1:%[0-9]+]]:gpr = ADDI %stack.1, 0
+  ; CHECK-NEXT:   VS8R_V killed [[VL8RE8_V]], killed [[ADDI1]] :: (store (<vscale x 1 x s512>) into %stack.1)
+  ; CHECK-NEXT:   INLINEASM &"vadd.vv $0, $0, $0", 25 /* sideeffect mayload maystore attdialect */, 262166 /* mem:m */, %stack.0.v, 0, 262166 /* mem:m */, %stack.1, 0
+  ; CHECK-NEXT:   PseudoRET
+entry:
+  %v = alloca <vscale x 64 x i8>, align 1
+  %0 = load <vscale x 64 x i8>, ptr %v, align 1
+  call void asm sideeffect "vadd.vv $0, $0, $0", "=*imr,imr"(ptr elementtype(<vscale x 64 x i8>) %v, <vscale x 64 x i8> %0)
+  ret void
+}

[preames]

LGTM