[RISCV] Save vector registers in interrupt handler. (#143808)

Corresponding gcc bug report
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=110665

The generated code is pretty awful.

Author: topperc

llvm/lib/Target/RISCV/RISCVCallingConv.td

@@ -56,14 +56,40 @@ def CSR_XLEN_F32_Interrupt: CalleeSavedRegs<(add CSR_Interrupt,
 def CSR_XLEN_F64_Interrupt: CalleeSavedRegs<(add CSR_Interrupt,
                                              (sequence "F%u_D", 0, 31))>;
 
+// Same as CSR_Interrupt, but including all vector registers.
+def CSR_XLEN_V_Interrupt: CalleeSavedRegs<(add CSR_Interrupt,
+                                           (sequence "V%u", 0, 31))>;
+
+// Same as CSR_Interrupt, but including all 32-bit FP registers and all vector
+// registers.
+def CSR_XLEN_F32_V_Interrupt: CalleeSavedRegs<(add CSR_XLEN_F32_Interrupt,
+                                               (sequence "V%u", 0, 31))>;
+
+// Same as CSR_Interrupt, but including all 64-bit FP registers and all vector
+// registers.
+def CSR_XLEN_F64_V_Interrupt: CalleeSavedRegs<(add CSR_XLEN_F64_Interrupt,
+                                               (sequence "V%u", 0, 31))>;
+
 // Same as CSR_Interrupt, but excluding X16-X31.
 def CSR_Interrupt_RVE : CalleeSavedRegs<(sub CSR_Interrupt,
                                         (sequence "X%u", 16, 31))>;
 
 // Same as CSR_XLEN_F32_Interrupt, but excluding X16-X31.
 def CSR_XLEN_F32_Interrupt_RVE: CalleeSavedRegs<(sub CSR_XLEN_F32_Interrupt,
-                                                (sequence "X%u", 16, 31))>;
+                                                 (sequence "X%u", 16, 31))>;
 
 // Same as CSR_XLEN_F64_Interrupt, but excluding X16-X31.
 def CSR_XLEN_F64_Interrupt_RVE: CalleeSavedRegs<(sub CSR_XLEN_F64_Interrupt,
-                                                (sequence "X%u", 16, 31))>;
+                                                 (sequence "X%u", 16, 31))>;
+
+// Same as CSR_XLEN_V_Interrupt, but excluding X16-X31.
+def CSR_XLEN_V_Interrupt_RVE: CalleeSavedRegs<(sub CSR_XLEN_V_Interrupt,
+                                               (sequence "X%u", 16, 31))>;
+
+// Same as CSR_XLEN_F32_V_Interrupt, but excluding X16-X31.
+def CSR_XLEN_F32_V_Interrupt_RVE: CalleeSavedRegs<(sub CSR_XLEN_F32_V_Interrupt,
+                                                   (sequence "X%u", 16, 31))>;
+
+// Same as CSR_XLEN_F64_V_Interrupt, but excluding X16-X31.
+def CSR_XLEN_F64_V_Interrupt_RVE: CalleeSavedRegs<(sub CSR_XLEN_F64_V_Interrupt,
+                                                   (sequence "X%u", 16, 31))>;

llvm/lib/Target/RISCV/RISCVRegisterInfo.cpp

@@ -69,6 +69,16 @@ RISCVRegisterInfo::getCalleeSavedRegs(const MachineFunction *MF) const {
   if (MF->getFunction().getCallingConv() == CallingConv::GHC)
     return CSR_NoRegs_SaveList;
   if (MF->getFunction().hasFnAttribute("interrupt")) {
+    if (Subtarget.hasVInstructions()) {
+      if (Subtarget.hasStdExtD())
+        return Subtarget.hasStdExtE() ? CSR_XLEN_F64_V_Interrupt_RVE_SaveList
+                                      : CSR_XLEN_F64_V_Interrupt_SaveList;
+      if (Subtarget.hasStdExtF())
+        return Subtarget.hasStdExtE() ? CSR_XLEN_F32_V_Interrupt_RVE_SaveList
+                                      : CSR_XLEN_F32_V_Interrupt_SaveList;
+      return Subtarget.hasStdExtE() ? CSR_XLEN_V_Interrupt_RVE_SaveList
+                                    : CSR_XLEN_V_Interrupt_SaveList;
+    }
     if (Subtarget.hasStdExtD())
       return Subtarget.hasStdExtE() ? CSR_XLEN_F64_Interrupt_RVE_SaveList
                                     : CSR_XLEN_F64_Interrupt_SaveList;