Index: llvm/lib/Target/RISCV/RISCVFrameLowering.cpp
===================================================================
--- llvm/lib/Target/RISCV/RISCVFrameLowering.cpp
+++ llvm/lib/Target/RISCV/RISCVFrameLowering.cpp
@@ -687,7 +687,10 @@
       Offset += StackOffset::getFixed(FirstSPAdjustAmount);
     else
       Offset += StackOffset::getFixed(getStackSizeWithRVVPadding(MF));
-  } else if (RI->hasStackRealignment(MF) && !MFI.isFixedObjectIndex(FI)) {
+    return Offset;
+  }
+
+  if (RI->hasStackRealignment(MF) && !MFI.isFixedObjectIndex(FI)) {
     // If the stack was realigned, the frame pointer is set in order to allow
     // SP to be restored, so we need another base register to record the stack
     // after realignment.
@@ -727,95 +730,90 @@
       assert(!MFI.hasVarSizedObjects());
       FrameReg = RISCV::X2;
     }
+  } else {
+    FrameReg = RI->getFrameRegister(MF);
+  }
+
+  if (FrameReg == getFPReg(STI)) {
+    Offset += StackOffset::getFixed(RVFI->getVarArgsSaveSize());
+    if (FI >= 0)
+      Offset -= StackOffset::getFixed(RVFI->getLibCallStackSize());
+    // When using FP to access scalable vector objects, we need to minus
+    // the frame size.
+    //
+    // |--------------------------| -- <-- FP
+    // | callee-allocated save    | |
+    // | area for register varargs| |
+    // |--------------------------| |
+    // | callee-saved registers   | |
+    // |--------------------------| | MFI.getStackSize()
+    // | scalar local variables   | |
+    // |--------------------------| -- (Offset of RVV objects is from here.)
+    // | RVV objects              |
+    // |--------------------------|
+    // | VarSize objects          |
+    // |--------------------------| <-- SP
+    if (MFI.getStackID(FI) == TargetStackID::ScalableVector) {
+      assert(!RI->hasStackRealignment(MF) &&
+             "can't index across variable sized realign");
+      // We don't expect any extra RVV alignment padding, as the stack size
+      // and RVV object sections should be correct aligned in their own
+      // right.
+      assert(MFI.getStackSize() == getStackSizeWithRVVPadding(MF) &&
+             "Inconsistent stack layout");
+      Offset -= StackOffset::getFixed(MFI.getStackSize());
+    }
+  } else {
+    // This case handles indexing off both SP and BP.
+    // If indexing off SP, there must not be any var sized objects
+    assert(FrameReg == RISCVABI::getBPReg() || !MFI.hasVarSizedObjects());
+
+    // When using SP to access frame objects, we need to add RVV stack size.
+    //
+    // |--------------------------| -- <-- FP
+    // | callee-allocated save    | | <----|
+    // | area for register varargs| |      |
+    // |--------------------------| |      |
+    // | callee-saved registers   | |      |
+    // |--------------------------| --     |
+    // | RVV alignment padding    | |      |
+    // | (not counted in          | |      |
+    // | MFI.getStackSize() but   | |      |
+    // | counted in               | |      |
+    // | RVFI.getRVVStackSize())  | |      |
+    // |--------------------------| --     |
+    // | RVV objects              | |      |-- MFI.getStackSize()
+    // | (not counted in          | |      |
+    // | MFI.getStackSize())      | |      |
+    // |--------------------------| --     |
+    // | padding before RVV       | |      |
+    // | (not counted in          | |      |
+    // | MFI.getStackSize())      | |      |
+    // |--------------------------| --     |
+    // | scalar local variables   | | <----'
+    // |--------------------------| -- <-- SP
+    //
     // The total amount of padding surrounding RVV objects is described by
     // RVV->getRVVPadding() and it can be zero. It allows us to align the RVV
     // objects to the required alignment.
     if (MFI.getStackID(FI) == TargetStackID::Default) {
-      Offset += StackOffset::getFixed(MFI.getStackSize());
-      assert(FI >= 0 && "Unhandled negative frame index");
+      if (MFI.isFixedObjectIndex(FI)) {
+        assert(!RI->hasStackRealignment(MF) &&
+               "can't index across variable sized realign");
+        Offset += StackOffset::get(getStackSizeWithRVVPadding(MF) +
+                                   RVFI->getLibCallStackSize(),
+                                   RVFI->getRVVStackSize());
+      } else {
+        Offset += StackOffset::getFixed(MFI.getStackSize());
+      }
     } else if (MFI.getStackID(FI) == TargetStackID::ScalableVector) {
       // Ensure the base of the RVV stack is correctly aligned: add on the
       // alignment padding.
-      int ScalarLocalVarSize = MFI.getStackSize() -
-                               RVFI->getCalleeSavedStackSize() +
-                               RVFI->getRVVPadding();
+      int ScalarLocalVarSize =
+        MFI.getStackSize() - RVFI->getCalleeSavedStackSize() -
+        RVFI->getVarArgsSaveSize() + RVFI->getRVVPadding();
       Offset += StackOffset::get(ScalarLocalVarSize, RVFI->getRVVStackSize());
     }
-  } else {
-    FrameReg = RI->getFrameRegister(MF);
-    if (hasFP(MF)) {
-      Offset += StackOffset::getFixed(RVFI->getVarArgsSaveSize());
-      if (FI >= 0)
-        Offset -= StackOffset::getFixed(RVFI->getLibCallStackSize());
-      // When using FP to access scalable vector objects, we need to minus
-      // the frame size.
-      //
-      // |--------------------------| -- <-- FP
-      // | callee-allocated save    | |
-      // | area for register varargs| |
-      // |--------------------------| |
-      // | callee-saved registers   | |
-      // |--------------------------| | MFI.getStackSize()
-      // | scalar local variables   | |
-      // |--------------------------| -- (Offset of RVV objects is from here.)
-      // | RVV objects              |
-      // |--------------------------|
-      // | VarSize objects          |
-      // |--------------------------| <-- SP
-      if (MFI.getStackID(FI) == TargetStackID::ScalableVector) {
-        // We don't expect any extra RVV alignment padding, as the stack size
-        // and RVV object sections should be correct aligned in their own
-        // right.
-        assert(MFI.getStackSize() == getStackSizeWithRVVPadding(MF) &&
-               "Inconsistent stack layout");
-        Offset -= StackOffset::getFixed(MFI.getStackSize());
-      }
-    } else {
-      // When using SP to access frame objects, we need to add RVV stack size.
-      //
-      // |--------------------------| -- <-- FP
-      // | callee-allocated save    | | <----|
-      // | area for register varargs| |      |
-      // |--------------------------| |      |
-      // | callee-saved registers   | |      |
-      // |--------------------------| --     |
-      // | RVV alignment padding    | |      |
-      // | (not counted in          | |      |
-      // | MFI.getStackSize() but   | |      |
-      // | counted in               | |      |
-      // | RVFI.getRVVStackSize())  | |      |
-      // |--------------------------| --     |
-      // | RVV objects              | |      |-- MFI.getStackSize()
-      // | (not counted in          | |      |
-      // | MFI.getStackSize())      | |      |
-      // |--------------------------| --     |
-      // | padding before RVV       | |      |
-      // | (not counted in          | |      |
-      // | MFI.getStackSize())      | |      |
-      // |--------------------------| --     |
-      // | scalar local variables   | | <----'
-      // |--------------------------| -- <-- SP
-      //
-      // The total amount of padding surrounding RVV objects is described by
-      // RVV->getRVVPadding() and it can be zero. It allows us to align the RVV
-      // objects to the required alignment.
-      if (MFI.getStackID(FI) == TargetStackID::Default) {
-        if (MFI.isFixedObjectIndex(FI)) {
-          Offset += StackOffset::get(getStackSizeWithRVVPadding(MF) +
-                                         RVFI->getLibCallStackSize(),
-                                     RVFI->getRVVStackSize());
-        } else {
-          Offset += StackOffset::getFixed(MFI.getStackSize());
-        }
-      } else if (MFI.getStackID(FI) == TargetStackID::ScalableVector) {
-        // Ensure the base of the RVV stack is correctly aligned: add on the
-        // alignment padding.
-        int ScalarLocalVarSize =
-            MFI.getStackSize() - RVFI->getCalleeSavedStackSize() -
-            RVFI->getVarArgsSaveSize() + RVFI->getRVVPadding();
-        Offset += StackOffset::get(ScalarLocalVarSize, RVFI->getRVVStackSize());
-      }
-    }
   }
 
   return Offset;