[PATCH] D74596: [RISCV] Correct the CallPreservedMask for the function call in an interrupt handler

[Shiva Chen via Phabricator via llvm-commits]

shiva0217 created this revision.
shiva0217 added reviewers: asb, apazos, lenary, luismarques.
Herald added subscribers: evandro, sameer.abuasal, pzheng, s.egerton, Jim, benna, psnobl, jocewei, PkmX, rkruppe, the_o, brucehoult, MartinMosbeck, rogfer01, edward-jones, zzheng, MaskRay, jrtc27, kito-cheng, niosHD, sabuasal, simoncook, johnrusso, rbar, hiraditya.
Herald added a project: LLVM.

The patch fix the issue mentioned in https://bugs.llvm.org/show_bug.cgi?id=42984.

CallPreservedMask is used to describe the register liveness after a function call. The function call in an interrupt handler should use the same CallPreservedMask as normal functions. So that only callee save registers can live through the function call.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D74596

Files:
  llvm/lib/Target/RISCV/RISCVRegisterInfo.cpp
  llvm/test/CodeGen/RISCV/interrupt-attr-callee.ll


Index: llvm/test/CodeGen/RISCV/interrupt-attr-callee.ll
===================================================================
--- /dev/null
+++ llvm/test/CodeGen/RISCV/interrupt-attr-callee.ll
@@ -0,0 +1,70 @@
+; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py
+; RUN: llc -mtriple riscv32-unknown-elf -o - %s \
+; RUN: 2>&1 | FileCheck %s -check-prefix CHECK-RV32
+; RUN: llc -mtriple riscv32-unknown-elf -mattr=+f -o - %s \
+; RUN: 2>&1 | FileCheck %s -check-prefix CHECK-RV32-F
+; RUN: llc -mtriple riscv32-unknown-elf -mattr=+f,+d -o - %s \
+; RUN: 2>&1 | FileCheck %s -check-prefix CHECK-RV32-FD
+;
+; The test case check that the funciton call in a interrupt handler will use the
+; correct CallPreservedMask as normal function. So only callee saved registers
+; could live through the function call.
+
+define dso_local void @handler() nounwind {
+; CHECK-RV32-LABEL: handler:
+; CHECK-RV32:       # %bb.0: # %entry
+; CHECK-RV32-NEXT:    addi sp, sp, -16
+; CHECK-RV32-NEXT:    sw ra, 12(sp)
+; CHECK-RV32-NEXT:    sw s0, 8(sp)
+; CHECK-RV32-NEXT:    lui a0, 2
+; CHECK-RV32-NEXT:    addi a0, a0, 4
+; CHECK-RV32-NEXT:    call read
+; CHECK-RV32-NEXT:    mv s0, a0
+; CHECK-RV32-NEXT:    call callee
+; CHECK-RV32-NEXT:    mv a0, s0
+; CHECK-RV32-NEXT:    lw s0, 8(sp)
+; CHECK-RV32-NEXT:    lw ra, 12(sp)
+; CHECK-RV32-NEXT:    addi sp, sp, 16
+; CHECK-RV32-NEXT:    tail write
+;
+; CHECK-RV32-F-LABEL: handler:
+; CHECK-RV32-F:       # %bb.0: # %entry
+; CHECK-RV32-F-NEXT:    addi sp, sp, -16
+; CHECK-RV32-F-NEXT:    sw ra, 12(sp)
+; CHECK-RV32-F-NEXT:    sw s0, 8(sp)
+; CHECK-RV32-F-NEXT:    lui a0, 2
+; CHECK-RV32-F-NEXT:    addi a0, a0, 4
+; CHECK-RV32-F-NEXT:    call read
+; CHECK-RV32-F-NEXT:    mv s0, a0
+; CHECK-RV32-F-NEXT:    call callee
+; CHECK-RV32-F-NEXT:    mv a0, s0
+; CHECK-RV32-F-NEXT:    lw s0, 8(sp)
+; CHECK-RV32-F-NEXT:    lw ra, 12(sp)
+; CHECK-RV32-F-NEXT:    addi sp, sp, 16
+; CHECK-RV32-F-NEXT:    tail write
+;
+; CHECK-RV32-FD-LABEL: handler:
+; CHECK-RV32-FD:       # %bb.0: # %entry
+; CHECK-RV32-FD-NEXT:    addi sp, sp, -16
+; CHECK-RV32-FD-NEXT:    sw ra, 12(sp)
+; CHECK-RV32-FD-NEXT:    sw s0, 8(sp)
+; CHECK-RV32-FD-NEXT:    lui a0, 2
+; CHECK-RV32-FD-NEXT:    addi a0, a0, 4
+; CHECK-RV32-FD-NEXT:    call read
+; CHECK-RV32-FD-NEXT:    mv s0, a0
+; CHECK-RV32-FD-NEXT:    call callee
+; CHECK-RV32-FD-NEXT:    mv a0, s0
+; CHECK-RV32-FD-NEXT:    lw s0, 8(sp)
+; CHECK-RV32-FD-NEXT:    lw ra, 12(sp)
+; CHECK-RV32-FD-NEXT:    addi sp, sp, 16
+; CHECK-RV32-FD-NEXT:    tail write
+entry:
+  %call = tail call i32 @read(i32 8196)
+  tail call void bitcast (void (...)* @callee to void ()*)()
+  tail call void @write(i32 %call)
+  ret void
+}
+
+declare i32 @read(i32)
+declare void @callee(...)
+declare void @write(i32)
Index: llvm/lib/Target/RISCV/RISCVRegisterInfo.cpp
===================================================================
--- llvm/lib/Target/RISCV/RISCVRegisterInfo.cpp
+++ llvm/lib/Target/RISCV/RISCVRegisterInfo.cpp
@@ -156,13 +156,6 @@
 RISCVRegisterInfo::getCallPreservedMask(const MachineFunction & MF,
                                         CallingConv::ID /*CC*/) const {
   auto &Subtarget = MF.getSubtarget<RISCVSubtarget>();
-  if (MF.getFunction().hasFnAttribute("interrupt")) {
-    if (Subtarget.hasStdExtD())
-      return CSR_XLEN_F64_Interrupt_RegMask;
-    if (Subtarget.hasStdExtF())
-      return CSR_XLEN_F32_Interrupt_RegMask;
-    return CSR_Interrupt_RegMask;
-  }
 
   switch (Subtarget.getTargetABI()) {
   default:


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