[LLVMdev] Dead Store Elimination

[Vinayak Borkar]

Hi,


Here is the result of optimization using the following passes:

llvm::createBasicAliasAnalysisPass()
llvm::createInstructionCombiningPass()
llvm::createReassociatePass()
llvm::createGVNPass()
llvm::createCFGSimplificationPass()


The optimized IR seems to contain what look like dead stores on %8 and 
%9 in basic blocks 7 and haveData. How can I get rid of them?

Thanks,
Vinayak

define internal void @block0() {
entry:
   %0 = call i8* @RNI_File_new()
   %1 = call i64 @RNI_File_open(i8* %0, i8* getelementptr inbounds ([69 
x i8]* @.str, i64 0, i64 0), i8 0)
   %2 = icmp eq i64 %1, 0
   br i1 %2, label %openSuccessBB, label %errorExit0

errorExit0:                                       ; preds = %entry, %5
   call void @RNI_File_delete(i8* %0)
   ret void

openSuccessBB:                                    ; preds = %entry
   %3 = call i8* @RNI_Memory_alloc(i64 1048576)
   %4 = icmp eq i8* %3, null
   br i1 %4, label %5, label %7

; <label>:5                                       ; preds = %checkErr, 
%openSuccessBB
   %6 = call i64 @RNI_File_close(i8* %0)
   br label %errorExit0

; <label>:7                                       ; preds = %openSuccessBB
   %8 = alloca i64, align 8
   store i64 1048576, i64* %8, align 8
   %9 = alloca i8*, align 8
   store i8* %3, i8** %9, align 8
   br label %fileReadBB

fileReadBB:                                       ; preds = %haveData, %7
   %10 = call i64 @RNI_File_read(i8* %0, i8* %3, i64 1048576)
   %11 = icmp sgt i64 %10, 0
   br i1 %11, label %haveData, label %checkErr

haveData:                                         ; preds = %fileReadBB
   store i8* %3, i8** %9, align 8
   store i64 1048576, i64* %8, align 8
   br label %fileReadBB

checkErr:                                         ; preds = %fileReadBB
   %12 = icmp eq i64 %10, 0
   call void @RNI_Memory_free(i8* %3)
   br i1 %12, label %eof, label %5

eof:                                              ; preds = %checkErr
   %13 = call i64 @RNI_File_close(i8* %0)
   call void @RNI_File_delete(i8* %0)
   ret void
}