[WinEH] Split EH_RESTORE out of CATCHRET for 32-bit EH
This adds the EH_RESTORE x86 pseudo instr, which is responsible for
restoring the stack pointers: EBP and ESP, and ESI if stack realignment
is involved. We only need this on 32-bit x86, because on x64 the runtime
restores CSRs for us.
Previously we had to keep the CATCHRET instruction around during SEH so
that we could convince X86FrameLowering to restore our frame pointers.
Now we can split these instructions earlier.
This was confusing, because we had a return instruction which wasn't
really a return and was ultimately going to be removed by
X86FrameLowering. This change also simplifies X86FrameLowering, which
really shouldn't be building new MBBs.
No observable functional change currently, but with the new register
mask stuff in D14407, CATCHRET will become a register allocator barrier,
and our existing tests rely on us having reasonable register allocation
around SEH.
llvm-svn: 252266
diff --git a/llvm/lib/Target/X86/X86InstrCompiler.td b/llvm/lib/Target/X86/X86InstrCompiler.td
index 3e16eed..f35fd5c 100644
--- a/llvm/lib/Target/X86/X86InstrCompiler.td
+++ b/llvm/lib/Target/X86/X86InstrCompiler.td
@@ -152,13 +152,25 @@
}
-let isTerminator = 1, hasSideEffects = 1, isBarrier = 1, hasCtrlDep = 1, isCodeGenOnly = 1, isReturn = 1 in {
-def CATCHRET : I<0, Pseudo, (outs), (ins brtarget32:$dst, brtarget32:$from),
- "# CATCHRET",
- [(catchret bb:$dst, bb:$from)]>;
-def CLEANUPRET : I<0, Pseudo, (outs), (ins), "# CLEANUPRET", [(cleanupret)]>;
+let isTerminator = 1, hasSideEffects = 1, isBarrier = 1, hasCtrlDep = 1,
+ isCodeGenOnly = 1, isReturn = 1 in {
+ def CLEANUPRET : I<0, Pseudo, (outs), (ins), "# CLEANUPRET", [(cleanupret)]>;
+
+ // CATCHRET needs a custom inserter for SEH nonsense.
+ let usesCustomInserter = 1 in
+ def CATCHRET : I<0, Pseudo, (outs), (ins brtarget32:$dst, brtarget32:$from),
+ "# CATCHRET",
+ [(catchret bb:$dst, bb:$from)]>;
}
+// This instruction is responsible for re-establishing stack pointers after an
+// exception has been caught and we are rejoining normal control flow in the
+// parent function or funclet. It generally sets ESP and EBP, and optionally
+// ESI. It is only needed for 32-bit WinEH, as the runtime restores CSRs for us
+// elsewhere.
+let hasSideEffects = 1, isBarrier = 1, hasCtrlDep = 1, isCodeGenOnly = 1 in
+def EH_RESTORE : I<0, Pseudo, (outs), (ins), "# EH_RESTORE", []>;
+
let hasSideEffects = 1, isBarrier = 1, isCodeGenOnly = 1,
usesCustomInserter = 1 in {
def EH_SjLj_SetJmp32 : I<0, Pseudo, (outs GR32:$dst), (ins i32mem:$buf),