//===----------------------------------------------------------------------===//
#define DEBUG_TYPE "block-placement2"
-#include "llvm/CodeGen/Passes.h"
-#include "llvm/CodeGen/MachineModuleInfo.h"
+#include "llvm/CodeGen/MachineBasicBlock.h"
#include "llvm/CodeGen/MachineBlockFrequencyInfo.h"
#include "llvm/CodeGen/MachineBranchProbabilityInfo.h"
#include "llvm/CodeGen/MachineFunction.h"
-#include "llvm/CodeGen/MachineBasicBlock.h"
#include "llvm/CodeGen/MachineFunctionPass.h"
+#include "llvm/CodeGen/MachineLoopInfo.h"
+#include "llvm/CodeGen/MachineModuleInfo.h"
+#include "llvm/CodeGen/Passes.h"
#include "llvm/Support/Allocator.h"
#include "llvm/Support/ErrorHandling.h"
#include "llvm/ADT/DenseMap.h"
#include "llvm/ADT/SmallVector.h"
#include "llvm/ADT/Statistic.h"
#include "llvm/Target/TargetInstrInfo.h"
+#include "llvm/Target/TargetLowering.h"
#include <algorithm>
using namespace llvm;
/// \brief A handle to the function-wide block frequency pass.
const MachineBlockFrequencyInfo *MBFI;
+ /// \brief A handle to the loop info.
+ const MachineLoopInfo *MLI;
+
/// \brief A handle to the target's instruction info.
const TargetInstrInfo *TII;
+ /// \brief A handle to the target's lowering info.
+ const TargetLowering *TLI;
+
/// \brief A prioritized list of edges in the BB-graph.
///
/// For each function, we insert all control flow edges between BBs, along
void BuildBlockChains();
void PrioritizeChains(MachineFunction &F);
void PlaceBlockChains(MachineFunction &F);
+ void AlignLoops(MachineFunction &F);
public:
static char ID; // Pass identification, replacement for typeid
void getAnalysisUsage(AnalysisUsage &AU) const {
AU.addRequired<MachineBranchProbabilityInfo>();
AU.addRequired<MachineBlockFrequencyInfo>();
+ AU.addRequired<MachineLoopInfo>();
MachineFunctionPass::getAnalysisUsage(AU);
}
"Branch Probability Basic Block Placement", false, false)
INITIALIZE_PASS_DEPENDENCY(MachineBranchProbabilityInfo)
INITIALIZE_PASS_DEPENDENCY(MachineBlockFrequencyInfo)
+INITIALIZE_PASS_DEPENDENCY(MachineLoopInfo)
INITIALIZE_PASS_END(MachineBlockPlacement, "block-placement2",
"Branch Probability Basic Block Placement", false, false)
}
}
+/// \brief Recursive helper to align a loop and any nested loops.
+static void AlignLoop(MachineFunction &F, MachineLoop *L, unsigned Align) {
+ // Recurse through nested loops.
+ for (MachineLoop::iterator I = L->begin(), E = L->end(); I != E; ++I)
+ AlignLoop(F, *I, Align);
+
+ L->getTopBlock()->setAlignment(Align);
+}
+
+/// \brief Align loop headers to target preferred alignments.
+void MachineBlockPlacement::AlignLoops(MachineFunction &F) {
+ if (F.getFunction()->hasFnAttr(Attribute::OptimizeForSize))
+ return;
+
+ unsigned Align = TLI->getPrefLoopAlignment();
+ if (!Align)
+ return; // Don't care about loop alignment.
+
+ for (MachineLoopInfo::iterator I = MLI->begin(), E = MLI->end(); I != E; ++I)
+ AlignLoop(F, *I, Align);
+}
+
bool MachineBlockPlacement::runOnMachineFunction(MachineFunction &F) {
// Check for single-block functions and skip them.
if (llvm::next(F.begin()) == F.end())
MBPI = &getAnalysis<MachineBranchProbabilityInfo>();
MBFI = &getAnalysis<MachineBlockFrequencyInfo>();
+ MLI = &getAnalysis<MachineLoopInfo>();
TII = F.getTarget().getInstrInfo();
+ TLI = F.getTarget().getTargetLowering();
assert(Edges.empty());
assert(BlockToChain.empty());
assert(PChains.empty());
BuildBlockChains();
PrioritizeChains(F);
PlaceBlockChains(F);
+ AlignLoops(F);
Edges.clear();
BlockToChain.clear();
declare void @error(i32 %i, i32 %a, i32 %b)
-define i32 @test1(i32 %i, i32* %a, i32 %b) {
+define i32 @test_ifchains(i32 %i, i32* %a, i32 %b) {
; Test a chain of ifs, where the block guarded by the if is error handling code
; that is not expected to run.
-; CHECK: test1:
+; CHECK: test_ifchains:
; CHECK: %entry
; CHECK: %else1
; CHECK: %else2
}
!0 = metadata !{metadata !"branch_weights", i32 4, i32 64}
+
+define i32 @test_loop_align(i32 %i, i32* %a) {
+; Check that we provide basic loop body alignment with the block placement
+; pass.
+; CHECK: test_loop_align:
+; CHECK: %entry
+; CHECK: .align 16,
+; CHECK-NEXT: %body
+; CHECK: %exit
+
+entry:
+ br label %body
+
+body:
+ %iv = phi i32 [ 0, %entry ], [ %next, %body ]
+ %base = phi i32 [ 0, %entry ], [ %sum, %body ]
+ %arrayidx = getelementptr inbounds i32* %a, i32 %iv
+ %0 = load i32* %arrayidx
+ %sum = add nsw i32 %0, %base
+ %next = add i32 %iv, 1
+ %exitcond = icmp eq i32 %next, %i
+ br i1 %exitcond, label %exit, label %body
+
+exit:
+ ret i32 %sum
+}
+
+define i32 @test_nested_loop_align(i32 %i, i32* %a, i32* %b) {
+; Check that we provide nested loop body alignment.
+; CHECK: test_nested_loop_align:
+; CHECK: %entry
+; CHECK: .align 16,
+; CHECK-NEXT: %loop.body.1
+; CHECK: .align 16,
+; CHECK-NEXT: %inner.loop.body
+; CHECK-NOT: .align
+; CHECK: %loop.body.2
+; CHECK: %exit
+
+entry:
+ br label %loop.body.1
+
+loop.body.1:
+ %iv = phi i32 [ 0, %entry ], [ %next, %loop.body.2 ]
+ %arrayidx = getelementptr inbounds i32* %a, i32 %iv
+ %bidx = load i32* %arrayidx
+ br label %inner.loop.body
+
+inner.loop.body:
+ %inner.iv = phi i32 [ 0, %loop.body.1 ], [ %inner.next, %inner.loop.body ]
+ %base = phi i32 [ 0, %loop.body.1 ], [ %sum, %inner.loop.body ]
+ %scaled_idx = mul i32 %bidx, %iv
+ %inner.arrayidx = getelementptr inbounds i32* %b, i32 %scaled_idx
+ %0 = load i32* %inner.arrayidx
+ %sum = add nsw i32 %0, %base
+ %inner.next = add i32 %iv, 1
+ %inner.exitcond = icmp eq i32 %inner.next, %i
+ br i1 %inner.exitcond, label %loop.body.2, label %inner.loop.body
+
+loop.body.2:
+ %next = add i32 %iv, 1
+ %exitcond = icmp eq i32 %next, %i
+ br i1 %exitcond, label %exit, label %loop.body.1
+
+exit:
+ ret i32 %sum
+}