[llvm] 0d40688 - [RISCV] Do not outline CFI instructions when they are needed in EH

[via llvm-commits]

Author: wangpc
Date: 2022-04-21T16:13:22+08:00
New Revision: 0d40688925a384088c149d1830dc0761a90364f7

URL: https://github.com/llvm/llvm-project/commit/0d40688925a384088c149d1830dc0761a90364f7
DIFF: https://github.com/llvm/llvm-project/commit/0d40688925a384088c149d1830dc0761a90364f7.diff

LOG: [RISCV] Do not outline CFI instructions when they are needed in EH

We saw a failure caused by unwinding with incomplete CFIs, so we
can't outline CFI instructions when they are needed in EH.

Reviewed By: luismarques

Differential Revision: https://reviews.llvm.org/D122634

Added: 
    

Modified: 
    llvm/lib/Target/RISCV/RISCVInstrInfo.cpp
    llvm/test/CodeGen/RISCV/machine-outliner-throw.ll

Removed: 
    


################################################################################
diff  --git a/llvm/lib/Target/RISCV/RISCVInstrInfo.cpp b/llvm/lib/Target/RISCV/RISCVInstrInfo.cpp
index 8f931c6ad1d9d..09b88c077964e 100644
--- a/llvm/lib/Target/RISCV/RISCVInstrInfo.cpp
+++ b/llvm/lib/Target/RISCV/RISCVInstrInfo.cpp
@@ -1246,7 +1246,12 @@ RISCVInstrInfo::getOutliningType(MachineBasicBlock::iterator &MBBI,
   if (MI.isPosition()) {
     // We can manually strip out CFI instructions later.
     if (MI.isCFIInstruction())
-      return outliner::InstrType::Invisible;
+      // If current function has exception handling code, we can't outline &
+      // strip these CFI instructions since it may break .eh_frame section
+      // needed in unwinding.
+      return MI.getMF()->getFunction().needsUnwindTableEntry()
+                 ? outliner::InstrType::Illegal
+                 : outliner::InstrType::Invisible;
 
     return outliner::InstrType::Illegal;
   }

diff  --git a/llvm/test/CodeGen/RISCV/machine-outliner-throw.ll b/llvm/test/CodeGen/RISCV/machine-outliner-throw.ll
index b0ac9c9da23a5..4c42f93cbb874 100644
--- a/llvm/test/CodeGen/RISCV/machine-outliner-throw.ll
+++ b/llvm/test/CodeGen/RISCV/machine-outliner-throw.ll
@@ -1,3 +1,4 @@
+; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py
 ; RUN: llc -verify-machineinstrs -enable-machine-outliner -mattr=+m -mtriple=riscv64 < %s | FileCheck %s
 
 ; Ensure that we won't outline CFIs when they are needed in unwinding.
@@ -5,7 +6,15 @@
 define i32 @func1(i32 %x) #0 {
 ; CHECK-LABEL: func1:
 ; CHECK:       # %bb.0: # %entry
-; CHECK-NEXT:    call t0, OUTLINED_FUNCTION_0
+; CHECK-NEXT:    addi sp, sp, -16
+; CHECK-NEXT:    .cfi_def_cfa_offset 16
+; CHECK-NEXT:    sd ra, 8(sp) # 8-byte Folded Spill
+; CHECK-NEXT:    sd s0, 0(sp) # 8-byte Folded Spill
+; CHECK-NEXT:    .cfi_offset ra, -8
+; CHECK-NEXT:    .cfi_offset s0, -16
+; CHECK-NEXT:    mulw a0, a0, a0
+; CHECK-NEXT:    addiw s0, a0, 1
+; CHECK-NEXT:    li a0, 4
 ; CHECK-NEXT:    call __cxa_allocate_exception at plt
 ; CHECK-NEXT:    sw s0, 0(a0)
 ; CHECK-NEXT:    lui a1, %hi(_ZTIi)
@@ -25,7 +34,15 @@ entry:
 define i32 @func2(i32 %x) #0 {
 ; CHECK-LABEL: func2:
 ; CHECK:       # %bb.0: # %entry
-; CHECK-NEXT:    call t0, OUTLINED_FUNCTION_0
+; CHECK-NEXT:    addi sp, sp, -16
+; CHECK-NEXT:    .cfi_def_cfa_offset 16
+; CHECK-NEXT:    sd ra, 8(sp) # 8-byte Folded Spill
+; CHECK-NEXT:    sd s0, 0(sp) # 8-byte Folded Spill
+; CHECK-NEXT:    .cfi_offset ra, -8
+; CHECK-NEXT:    .cfi_offset s0, -16
+; CHECK-NEXT:    mulw a0, a0, a0
+; CHECK-NEXT:    addiw s0, a0, 1
+; CHECK-NEXT:    li a0, 4
 ; CHECK-NEXT:    call __cxa_allocate_exception at plt
 ; CHECK-NEXT:    sw s0, 0(a0)
 ; CHECK-NEXT:    lui a1, %hi(_ZTIi)
@@ -42,15 +59,6 @@ entry:
   unreachable
 }
 
-; CHECK-LABEL: OUTLINED_FUNCTION_0:
-; CHECK:       # %bb.0:
-; CHECK-NEXT:    addi sp, sp, -16
-; CHECK-NEXT:    sd ra, 8(sp)
-; CHECK-NEXT:    sd s0, 0(sp)
-; CHECK-NEXT:    mulw a0, a0, a0
-; CHECK-NEXT:    addiw s0, a0, 1
-; CHECK-NEXT:    li a0, 4
-
 @_ZTIi = external constant i8*
 declare i8* @__cxa_allocate_exception(i64)
 declare void @__cxa_throw(i8*, i8*, i8*)