[PATCH] D20604: Codegen: Don't tail-duplicate blocks with un-analyzable fallthrough.
Kyle Butt via llvm-commits
llvm-commits at lists.llvm.org
Tue May 24 16:51:40 PDT 2016
iteratee removed rL LLVM as the repository for this revision.
iteratee updated this revision to Diff 58356.
iteratee added a comment.
Herald added a subscriber: joker.eph.
Tidied up test case.
http://reviews.llvm.org/D20604
Files:
lib/CodeGen/TailDuplicator.cpp
test/CodeGen/PowerPC/tail-dup-analyzable-fallthrough.ll
Index: test/CodeGen/PowerPC/tail-dup-analyzable-fallthrough.ll
===================================================================
--- /dev/null
+++ test/CodeGen/PowerPC/tail-dup-analyzable-fallthrough.ll
@@ -0,0 +1,59 @@
+; RUN: llc -O2 < %s | FileCheck %s
+target datalayout = "e-m:e-i64:64-n32:64"
+target triple = "powerpc64le--linux-gnu"
+
+%struct.HashBucket = type { %struct.HashBucket*, i64, i64* }
+; CHECK: divdu
+; CHECK: mulld
+; CHECK: sub
+; CHECK: b [[LOOPENTRY:[._0-9A-Za-z]+]]
+; CHECK: [[LOOPTOP:[._0-9A-Za-z]+]]:
+; CHECK-NOT: {{{[._0-9A-Za-z]+}}}:
+; CHECK: ld [[PTRREG:[0-9]+]], 0([[PTRREG]])
+; CHECK-NEXT: [[LOOPENTRY]]:
+; CHECK-NOT: {{{[._0-9A-Za-z]+}}}:
+; CHECK: cmpldi [[PTRREG]], 0
+; CHECK-NEXT: beqlr
+; Function Attrs: norecurse nounwind readonly
+define i64* @findKey(%struct.HashBucket** nocapture readonly %Buckets, i64 %BucketSize, i64 %Key) #0 {
+entry:
+ %mul.i = mul i64 %Key, 237
+ %shr.i = lshr i64 %mul.i, 16
+ %xor.i = xor i64 %shr.i, %Key
+ %rem = urem i64 %xor.i, %BucketSize
+ %arrayidx = getelementptr inbounds %struct.HashBucket*, %struct.HashBucket** %Buckets, i64 %rem
+ %current.012 = load %struct.HashBucket*, %struct.HashBucket** %arrayidx, align 8
+ %tobool13 = icmp eq %struct.HashBucket* %current.012, null
+ br i1 %tobool13, label %cond.end, label %land.rhs.preheader
+
+land.rhs.preheader: ; preds = %entry
+ br label %land.rhs
+
+land.rhs: ; preds = %land.rhs.preheader, %for.inc
+ %current.014 = phi %struct.HashBucket* [ %current.0, %for.inc ], [ %current.012, %land.rhs.preheader ]
+ %Key1 = getelementptr inbounds %struct.HashBucket, %struct.HashBucket* %current.014, i64 0, i32 1
+ %0 = load i64, i64* %Key1, align 8
+ %lnot = icmp eq i64 %0, %Key
+ br i1 %lnot, label %cond.true, label %for.inc
+
+for.inc: ; preds = %land.rhs
+ %Next = getelementptr inbounds %struct.HashBucket, %struct.HashBucket* %current.014, i64 0, i32 0
+ %current.0 = load %struct.HashBucket*, %struct.HashBucket** %Next, align 8
+ %tobool = icmp eq %struct.HashBucket* %current.0, null
+ br i1 %tobool, label %cond.end.loopexit, label %land.rhs
+
+cond.true: ; preds = %land.rhs
+ %current.014.lcssa = phi %struct.HashBucket* [ %current.014, %land.rhs ]
+ %Value = getelementptr inbounds %struct.HashBucket, %struct.HashBucket* %current.014.lcssa, i64 0, i32 2
+ %1 = load i64*, i64** %Value, align 8
+ br label %cond.end
+
+cond.end.loopexit: ; preds = %for.inc
+ br label %cond.end
+
+cond.end: ; preds = %cond.end.loopexit, %entry, %cond.true
+ %cond = phi i64* [ %1, %cond.true ], [ null, %entry ], [ null, %cond.end.loopexit ]
+ ret i64* %cond
+}
+
+attributes #0 = { norecurse nounwind readonly }
Index: lib/CodeGen/TailDuplicator.cpp
===================================================================
--- lib/CodeGen/TailDuplicator.cpp
+++ lib/CodeGen/TailDuplicator.cpp
@@ -592,6 +592,14 @@
}
}
+ // If the block to be duplicated ends in an unanalyzable fallthrough, don't
+ // duplicate it.
+ MachineBasicBlock *PredTBB = nullptr, *PredFBB = nullptr;
+ SmallVector<MachineOperand, 4> PredCond;
+ if (TII->AnalyzeBranch(TailBB, PredTBB, PredFBB, PredCond, true)
+ && TailBB.canFallThrough())
+ return false;
+
if (HasIndirectbr && PreRegAlloc)
return true;
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