[LLVMdev] How to require ScalarEvolution analysis in a Module pass?

[陈晓宇]

Guys,

What I want to do is to hack global opt pass, which needs ScalarEvolution
analysis. However opt crashed saying
"opt: /home/xchen/llvm/include/llvm/PassAnalysisSupport.h:242:
AnalysisType& llvm::Pass::getAnalysisID(const void*, llvm::Function&) [with
AnalysisType = llvm::ScalarEvolution]: Assertion `ResultPass && "Unable to
find requested analysis info"' failed.".

My question is what should I do to require ScalarEvolution analysis in a
Module pass???

Steps to reproduce(bc file attached in case you do not have clang
installed):

1. Makefile looks like this:
all:
    clang test.c -disable-llvm-optzns -emit-llvm -S
    llvm-as test.s -o test.bc
    opt test.bc -loop-unroll -globalopt -loop-unroll -inline -loop-idiom -o
out.bc
    llvm-dis < out.bc > out.ll
2. test.c:
#include <stdio.h>

int A[100];
static int toBeInlined(int A[100]) {
    int ans = 0;
    for (int i=0; i<100; ++i)
        ans+=A[i];
    return ans;
}

int main() {
    for (int i=0; i<100; ++i)
        if (i%3==0)
            A[i] = i;
        else
            A[i] = i+1;
    int ans = toBeInlined(A);
    printf("%d\n", ans);
    return 0;
}

3. globalopt:
--- GlobalOpt.cpp       (revision 162438)
+++ GlobalOpt.cpp       (working copy)
@@ -38,6 +38,7 @@
 #include "llvm/ADT/SmallVector.h"
 #include "llvm/ADT/Statistic.h"
 #include "llvm/ADT/STLExtras.h"
+#include "llvm/Analysis/ScalarEvolutionExpander.h"
 #include <algorithm>
 using namespace llvm;

@@ -63,6 +64,7 @@
   struct GlobalOpt : public ModulePass {
     virtual void getAnalysisUsage(AnalysisUsage &AU) const {
       AU.addRequired<TargetLibraryInfo>();
+      AU.addRequired<ScalarEvolution>();
     }
     static char ID; // Pass identification, replacement for typeid
     GlobalOpt() : ModulePass(ID) {
@@ -92,6 +94,7 @@
 INITIALIZE_PASS_BEGIN(GlobalOpt, "globalopt",
                 "Global Variable Optimizer", false, false)
 INITIALIZE_PASS_DEPENDENCY(TargetLibraryInfo)
+INITIALIZE_PASS_DEPENDENCY(ScalarEvolution)
 INITIALIZE_PASS_END(GlobalOpt, "globalopt",
                 "Global Variable Optimizer", false, false)

@@ -2087,6 +2090,7 @@
     if (!F->hasName() && !F->isDeclaration())
       F->setLinkage(GlobalValue::InternalLinkage);
     F->removeDeadConstantUsers();
+  ScalarEvolution *SE = &getAnalysis<ScalarEvolution>(*F);
 ------------------------------------> CRASH here:
     if (F->isDefTriviallyDead()) {
       F->eraseFromParent();
       Changed = true;

4. core dump
#0  0x000000386de30265 in raise () from /lib64/libc.so.6
#1  0x000000386de31d10 in abort () from /lib64/libc.so.6
#2  0x000000386de296e6 in __assert_fail () from /lib64/libc.so.6
#3  0x000000000058dbe1 in llvm::Pass::getAnalysisID<llvm::ScalarEvolution>
(this=0x10e9ef0, PI=0x10d3120, F=
    ...) at /home/xchen/llvm/include/llvm/PassAnalysisSupport.h:242
#4  0x000000000058dc4c in llvm::Pass::getAnalysis<llvm::ScalarEvolution>
(this=0x10e9ef0, F=...)
    at /home/xchen/llvm/include/llvm/PassAnalysisSupport.h:231
#5  0x0000000000577f60 in (anonymous
namespace)::GlobalOpt::OptimizeFunctions (this=0x10e9ef0, M=...)
    at /home/xchen/llvm/lib/Transforms/IPO/GlobalOpt.cpp:2093
#6  0x00000000005824c5 in (anonymous namespace)::GlobalOpt::runOnModule
(this=0x10e9ef0, M=...)
    at /home/xchen/llvm/lib/Transforms/IPO/GlobalOpt.cpp:3130
#7  0x0000000000a50c69 in llvm::MPPassManager::runOnModule (this=0x10f4120,
M=...)
    at /home/xchen/llvm/lib/VMCore/PassManager.cpp:1572
#8  0x0000000000a520d9 in llvm::PassManagerImpl::run (this=0x10f44a0, M=...)
    at /home/xchen/llvm/lib/VMCore/PassManager.cpp:1655
#9  0x0000000000a5213b in llvm::PassManager::run (this=0x7fffffffd510,
M=...)
    at /home/xchen/llvm/lib/VMCore/PassManager.cpp:1684
#10 0x0000000000541e77 in main (argc=9, argv=0x7fffffffd778) at
/home/xchen/llvm/tools/opt/opt.cpp:745
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