[llvm-commits] [llvm] r53038 - in /llvm/trunk: lib/Transforms/Scalar/ADCE.cpp test/Transforms/ADCE/2008-07-02-Unreachable.ll
Owen Anderson
resistor at mac.com
Wed Jul 2 11:05:24 PDT 2008
Author: resistor
Date: Wed Jul 2 13:05:19 2008
New Revision: 53038
URL: http://llvm.org/viewvc/llvm-project?rev=53038&view=rev
Log:
Add support to ADCE for pruning unreachable blocks. This addresses the final
part of PR2509.
Added:
llvm/trunk/test/Transforms/ADCE/2008-07-02-Unreachable.ll
Modified:
llvm/trunk/lib/Transforms/Scalar/ADCE.cpp
Modified: llvm/trunk/lib/Transforms/Scalar/ADCE.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/Scalar/ADCE.cpp?rev=53038&r1=53037&r2=53038&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/Scalar/ADCE.cpp (original)
+++ llvm/trunk/lib/Transforms/Scalar/ADCE.cpp Wed Jul 2 13:05:19 2008
@@ -16,12 +16,15 @@
#define DEBUG_TYPE "adce"
#include "llvm/Transforms/Scalar.h"
+#include "llvm/BasicBlock.h"
#include "llvm/Instructions.h"
#include "llvm/Pass.h"
+#include "llvm/Support/CFG.h"
#include "llvm/Support/Compiler.h"
#include "llvm/Support/InstIterator.h"
-#include "llvm/ADT/Statistic.h"
#include "llvm/ADT/DenseSet.h"
+#include "llvm/ADT/DepthFirstIterator.h"
+#include "llvm/ADT/Statistic.h"
#include "llvm/ADT/SmallVector.h"
using namespace llvm;
@@ -36,6 +39,9 @@
DenseSet<Instruction*> alive;
SmallVector<Instruction*, 1024> worklist;
+ DenseSet<BasicBlock*> reachable;
+ SmallVector<BasicBlock*, 1024> unreachable;
+
virtual bool runOnFunction(Function& F);
virtual void getAnalysisUsage(AnalysisUsage& AU) const {
@@ -51,6 +57,42 @@
bool ADCE::runOnFunction(Function& F) {
alive.clear();
worklist.clear();
+ reachable.clear();
+ unreachable.clear();
+
+ // First, collect the set of reachable blocks ...
+ for (df_iterator<BasicBlock*> DI = df_begin(&F.getEntryBlock()),
+ DE = df_end(&F.getEntryBlock()); DI != DE; ++DI)
+ reachable.insert(*DI);
+
+ // ... and then invert it into the list of unreachable ones. These
+ // blocks will be removed from the function.
+ for (Function::iterator FI = F.begin(), FE = F.end(); FI != FE; ++FI)
+ if (!reachable.count(FI))
+ unreachable.push_back(FI);
+
+ // Prepare to remove blocks by removing the PHI node entries for those blocks
+ // in their successors, and remove them from reference counting.
+ for (SmallVector<BasicBlock*, 1024>::iterator UI = unreachable.begin(),
+ UE = unreachable.end(); UI != UE; ++UI) {
+ BasicBlock* BB = *UI;
+ for (succ_iterator SI = succ_begin(BB), SE = succ_end(BB);
+ SI != SE; ++SI) {
+ BasicBlock* succ = *SI;
+ BasicBlock::iterator succ_inst = succ->begin();
+ while (PHINode* P = dyn_cast<PHINode>(succ_inst)) {
+ P->removeIncomingValue(BB);
+ ++succ_inst;
+ }
+ }
+
+ BB->dropAllReferences();
+ }
+
+ // Finally, erase the unreachable blocks.
+ for (SmallVector<BasicBlock*, 1024>::iterator UI = unreachable.begin(),
+ UE = unreachable.end(); UI != UE; ++UI)
+ (*UI)->eraseFromParent();
// Collect the set of "root" instructions that are known live.
for (inst_iterator I = inst_begin(F), E = inst_end(F); I != E; ++I)
Added: llvm/trunk/test/Transforms/ADCE/2008-07-02-Unreachable.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/ADCE/2008-07-02-Unreachable.ll?rev=53038&view=auto
==============================================================================
--- llvm/trunk/test/Transforms/ADCE/2008-07-02-Unreachable.ll (added)
+++ llvm/trunk/test/Transforms/ADCE/2008-07-02-Unreachable.ll Wed Jul 2 13:05:19 2008
@@ -0,0 +1,37 @@
+; RUN: llvm-as < %s | opt -adce -simplifycfg | llvm-dis | not grep forcond
+; PR2509
+
+target datalayout = "e-p:32:32:32-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:32:64-f32:32:32-f64:32:64-v64:64:64-v128:128:128-a0:0:64-f80:128:128"
+target triple = "i686-apple-darwin9.3.0"
+ at g_3 = external global i8 ; <i8*> [#uses=2]
+
+define i32 @func_1() nounwind {
+entry:
+ br i1 false, label %ifelse, label %ifthen
+
+ifthen: ; preds = %entry
+ br label %ifend
+
+ifelse: ; preds = %entry
+ %tmp3 = load i8* @g_3 ; <i8> [#uses=0]
+ br label %forcond.thread
+
+forcond.thread: ; preds = %ifelse
+ br label %afterfor
+
+forcond: ; preds = %forinc
+ br i1 false, label %afterfor, label %forbody
+
+forbody: ; preds = %forcond
+ br label %forinc
+
+forinc: ; preds = %forbody
+ br label %forcond
+
+afterfor: ; preds = %forcond, %forcond.thread
+ %tmp10 = load i8* @g_3 ; <i8> [#uses=0]
+ br label %ifend
+
+ifend: ; preds = %afterfor, %ifthen
+ ret i32 0
+}
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