diff options
| -rw-r--r-- | llvm/lib/CodeGen/XRayInstrumentation.cpp | 46 | ||||
| -rw-r--r-- | llvm/test/CodeGen/X86/xray-loop-detection.ll | 23 |
2 files changed, 53 insertions, 16 deletions
diff --git a/llvm/lib/CodeGen/XRayInstrumentation.cpp b/llvm/lib/CodeGen/XRayInstrumentation.cpp index 7d2848bdc13..2df3602733f 100644 --- a/llvm/lib/CodeGen/XRayInstrumentation.cpp +++ b/llvm/lib/CodeGen/XRayInstrumentation.cpp @@ -18,6 +18,8 @@ #include "llvm/CodeGen/MachineFunction.h" #include "llvm/CodeGen/MachineFunctionPass.h" #include "llvm/CodeGen/MachineInstrBuilder.h" +#include "llvm/CodeGen/MachineLoopInfo.h" +#include "llvm/CodeGen/MachineDominators.h" #include "llvm/CodeGen/Passes.h" #include "llvm/Support/TargetRegistry.h" #include "llvm/Target/TargetInstrInfo.h" @@ -33,6 +35,14 @@ struct XRayInstrumentation : public MachineFunctionPass { initializeXRayInstrumentationPass(*PassRegistry::getPassRegistry()); } + void getAnalysisUsage(AnalysisUsage &AU) const override { + AU.setPreservesCFG(); + AU.addRequired<MachineLoopInfo>(); + AU.addPreserved<MachineLoopInfo>(); + AU.addPreserved<MachineDominatorTree>(); + MachineFunctionPass::getAnalysisUsage(AU); + } + bool runOnMachineFunction(MachineFunction &MF) override; private: @@ -43,7 +53,7 @@ private: // This is the approach to go on CPUs which have a single RET instruction, // like x86/x86_64. void replaceRetWithPatchableRet(MachineFunction &MF, - const TargetInstrInfo *TII); + const TargetInstrInfo *TII); // Prepend the original return instruction with the exit sled code ("patchable // function exit" pseudo-instruction), preserving the original return @@ -54,13 +64,12 @@ private: // have to call the trampoline and return from it to the original return // instruction of the function being instrumented. void prependRetWithPatchableExit(MachineFunction &MF, - const TargetInstrInfo *TII); + const TargetInstrInfo *TII); }; } // anonymous namespace -void XRayInstrumentation::replaceRetWithPatchableRet(MachineFunction &MF, - const TargetInstrInfo *TII) -{ +void XRayInstrumentation::replaceRetWithPatchableRet( + MachineFunction &MF, const TargetInstrInfo *TII) { // We look for *all* terminators and returns, then replace those with // PATCHABLE_RET instructions. SmallVector<MachineInstr *, 4> Terminators; @@ -91,9 +100,8 @@ void XRayInstrumentation::replaceRetWithPatchableRet(MachineFunction &MF, I->eraseFromParent(); } -void XRayInstrumentation::prependRetWithPatchableExit(MachineFunction &MF, - const TargetInstrInfo *TII) -{ +void XRayInstrumentation::prependRetWithPatchableExit( + MachineFunction &MF, const TargetInstrInfo *TII) { for (auto &MBB : MF) { for (auto &T : MBB.terminators()) { unsigned Opc = 0; @@ -106,7 +114,7 @@ void XRayInstrumentation::prependRetWithPatchableExit(MachineFunction &MF, if (Opc != 0) { // Prepend the return instruction with PATCHABLE_FUNCTION_EXIT or // PATCHABLE_TAIL_CALL . - BuildMI(MBB, T, T.getDebugLoc(),TII->get(Opc)); + BuildMI(MBB, T, T.getDebugLoc(), TII->get(Opc)); } } } @@ -125,8 +133,13 @@ bool XRayInstrumentation::runOnMachineFunction(MachineFunction &MF) { return false; // XRay threshold attribute not found. if (Attr.getValueAsString().getAsInteger(10, XRayThreshold)) return false; // Invalid value for threshold. - if (F.size() < XRayThreshold) - return false; // Function is too small. + + // Check if we have a loop. + // FIXME: Maybe make this smarter, and see whether the loops are dependent + // on inputs or side-effects? + MachineLoopInfo &MLI = getAnalysis<MachineLoopInfo>(); + if (MLI.empty() && F.size() < XRayThreshold) + return false; // Function is too small and has no loops. } // We look for the first non-empty MachineBasicBlock, so that we can insert @@ -142,12 +155,10 @@ bool XRayInstrumentation::runOnMachineFunction(MachineFunction &MF) { if (!MF.getSubtarget().isXRaySupported()) { FirstMI.emitError("An attempt to perform XRay instrumentation for an" - " unsupported target."); + " unsupported target."); return false; } - // FIXME: Do the loop triviality analysis here or in an earlier pass. - // First, insert an PATCHABLE_FUNCTION_ENTER as the first instruction of the // MachineFunction. BuildMI(FirstMBB, FirstMI, FirstMI.getDebugLoc(), @@ -176,5 +187,8 @@ bool XRayInstrumentation::runOnMachineFunction(MachineFunction &MF) { char XRayInstrumentation::ID = 0; char &llvm::XRayInstrumentationID = XRayInstrumentation::ID; -INITIALIZE_PASS(XRayInstrumentation, "xray-instrumentation", "Insert XRay ops", - false, false) +INITIALIZE_PASS_BEGIN(XRayInstrumentation, "xray-instrumentation", + "Insert XRay ops", false, false) +INITIALIZE_PASS_DEPENDENCY(MachineLoopInfo) +INITIALIZE_PASS_END(XRayInstrumentation, "xray-instrumentation", + "Insert XRay ops", false, false) diff --git a/llvm/test/CodeGen/X86/xray-loop-detection.ll b/llvm/test/CodeGen/X86/xray-loop-detection.ll new file mode 100644 index 00000000000..3cd6b4aa6f8 --- /dev/null +++ b/llvm/test/CodeGen/X86/xray-loop-detection.ll @@ -0,0 +1,23 @@ +; RUN: llc -filetype=asm -o - -mtriple=x86_64-unknown-linux-gnu < %s | FileCheck %s +; RUN: llc -filetype=asm -o - -mtriple=x86_64-darwin-unknown < %s | FileCheck %s + +define i32 @foo(i32 %i) nounwind noinline uwtable "xray-instruction-threshold"="1" { +entry: + br label %Test +Test: + %indvar = phi i32 [0, %entry], [%nextindvar, %Inc] + %cond = icmp eq i32 %indvar, %i + br i1 %cond, label %Exit, label %Inc +Inc: + %nextindvar = add i32 %indvar, 1 + br label %Test +Exit: + %retval = phi i32 [%indvar, %Test] + ret i32 %retval +} + +; CHECK-LABEL: xray_sled_0: +; CHECK-NEXT: .ascii "\353\t" +; CHECK-NEXT: nopw 512(%rax,%rax) +; CHECK-LABEL: Ltmp0: + |
