Implement builtin_{setjmp/longjmp} on PPC
This implements SJLJ lowering on PPC, making the Clang functions
__builtin_{setjmp/longjmp} functional on PPC platforms. The implementation
strategy is similar to that on X86, with the exception that a branch-and-link
variant is used to get the right jump address. Credit goes to Bill Schmidt for
suggesting the use of the unconditional bcl form (instead of the regular bl
instruction) to limit return-address-cache pollution.
Benchmarking the speed at -O3 of:
static jmp_buf env_sigill;
void foo() {
__builtin_longjmp(env_sigill,1);
}
main() {
...
for (int i = 0; i < c; ++i) {
if (__builtin_setjmp(env_sigill)) {
goto done;
} else {
foo();
}
done:;
}
...
}
vs. the same code using the libc setjmp/longjmp functions on a P7 shows that
this builtin implementation is ~4x faster with Altivec enabled and ~7.25x
faster with Altivec disabled. This comparison is somewhat unfair because the
libc version must also save/restore the VSX registers which we don't yet
support.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@177666 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Target/PowerPC/PPCISelLowering.h b/lib/Target/PowerPC/PPCISelLowering.h
index 8d44d9f..1b0427e 100644
--- a/lib/Target/PowerPC/PPCISelLowering.h
+++ b/lib/Target/PowerPC/PPCISelLowering.h
@@ -16,6 +16,7 @@
#define LLVM_TARGET_POWERPC_PPC32ISELLOWERING_H
#include "PPC.h"
+#include "PPCRegisterInfo.h"
#include "PPCSubtarget.h"
#include "llvm/CodeGen/SelectionDAG.h"
#include "llvm/Target/TargetLowering.h"
@@ -119,6 +120,12 @@
/// are undefined.
MFCR,
+ // EH_SJLJ_SETJMP - SjLj exception handling setjmp.
+ EH_SJLJ_SETJMP,
+
+ // EH_SJLJ_LONGJMP - SjLj exception handling longjmp.
+ EH_SJLJ_LONGJMP,
+
/// RESVEC = VCMP(LHS, RHS, OPC) - Represents one of the altivec VCMP*
/// instructions. For lack of better number, we use the opcode number
/// encoding for the OPC field to identify the compare. For example, 838
@@ -321,6 +328,7 @@
class PPCTargetLowering : public TargetLowering {
const PPCSubtarget &PPCSubTarget;
+ const PPCRegisterInfo *PPCRegInfo;
public:
explicit PPCTargetLowering(PPCTargetMachine &TM);
@@ -395,6 +403,12 @@
MachineBasicBlock *MBB,
bool is8bit, unsigned Opcode) const;
+ MachineBasicBlock *emitEHSjLjSetJmp(MachineInstr *MI,
+ MachineBasicBlock *MBB) const;
+
+ MachineBasicBlock *emitEHSjLjLongJmp(MachineInstr *MI,
+ MachineBasicBlock *MBB) const;
+
ConstraintType getConstraintType(const std::string &Constraint) const;
/// Examine constraint string and operand type and determine a weight value.
@@ -608,6 +622,9 @@
const SmallVectorImpl<ISD::InputArg> &Ins,
DebugLoc dl, SelectionDAG &DAG,
SmallVectorImpl<SDValue> &InVals) const;
+
+ SDValue lowerEH_SJLJ_SETJMP(SDValue Op, SelectionDAG &DAG) const;
+ SDValue lowerEH_SJLJ_LONGJMP(SDValue Op, SelectionDAG &DAG) const;
};
}