Hi,
Are there some built-in LLVM transformation pass, or written library code
that transforms LLVM::SwitchInst into if-condition statements (LLVM::
BranchInst)?
The purpose of the transformation is that we have a legacy program analyzer
that includes an LLVM pass manipulating if-condition statements. Statements
of LLVM::SwithchInst should have been handled in the same manner but was
not done. Thus to transform these SwitchInst to if-condition looks a viable
alternative for us.
To illustrate, I give a simple C snippet with 'switch' and the expected
transformation.
----------------------------------------
Original program:
* char grade; ... switch(grade) { case 'A' :
printf("Excellent!\n" ); break; case 'B' :
printf("Well
done\n" ); break; default : printf("Invalid
grade\n" ); }*
may be transformed to something like
*if (grad=='A') printf("Excellent!\n" );*
*else if (grad=='B') printf("Well done\n" );*
*else printf("Invalid grade\n" );*
-------------------------------------------------
Are you aware of such a transformation pass ? Thanks.
Zhoulai
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Hi Zhoulai If you just don’t want any switch statements, then take a look at LowerSwitch.cpp. I think it will do what you want. You can also invoke it with ‘opt -lowerswitch ...’. Thanks, Pete> On Jul 24, 2015, at 10:46 AM, Zhoulai <zell08v at gmail.com> wrote: > > Hi, > > Are there some built-in LLVM transformation pass, or written library code that transforms LLVM::SwitchInst into if-condition statements (LLVM:: BranchInst)? > > The purpose of the transformation is that we have a legacy program analyzer that includes an LLVM pass manipulating if-condition statements. Statements of LLVM::SwithchInst should have been handled in the same manner but was not done. Thus to transform these SwitchInst to if-condition looks a viable alternative for us. > > To illustrate, I give a simple C snippet with 'switch' and the expected transformation. > ---------------------------------------- > Original program: > > char grade; > ... > switch(grade) > { > case 'A' : > printf("Excellent!\n" ); > break; > case 'B' : > printf("Well done\n" ); > break; > > default : > printf("Invalid grade\n" ); > } > > may be transformed to something like > > if (grad=='A') > printf("Excellent!\n" ); > else if (grad=='B') > printf("Well done\n" ); > else > printf("Invalid grade\n" ); > ------------------------------------------------- > > Are you aware of such a transformation pass ? Thanks. > Zhoulai > _______________________________________________ > LLVM Developers mailing list > LLVMdev at cs.uiuc.edu http://llvm.cs.uiuc.edu > http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev-------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.llvm.org/pipermail/llvm-dev/attachments/20150724/c7053060/attachment.html>
> > On Jul 24, 2015, at 10:46 AM, Zhoulai <zell08v at gmail.com> wrote: > > Hi, > > Are there some built-in LLVM transformation pass, or written library code that transforms LLVM::SwitchInst into if-condition statements (LLVM:: BranchInst)?There is a -lowerswitch pass that rewrites switch instructions with a sequence of branches. http://llvm.org/docs/Passes.html#lowerswitch-lower-switchinsts-to-branches <http://llvm.org/docs/Passes.html#lowerswitch-lower-switchinsts-to-branches> thanks, chen> > The purpose of the transformation is that we have a legacy program analyzer that includes an LLVM pass manipulating if-condition statements. Statements of LLVM::SwithchInst should have been handled in the same manner but was not done. Thus to transform these SwitchInst to if-condition looks a viable alternative for us. > > To illustrate, I give a simple C snippet with 'switch' and the expected transformation. > ---------------------------------------- > Original program: > > char grade; > ... > switch(grade) > { > case 'A' : > printf("Excellent!\n" ); > break; > case 'B' : > printf("Well done\n" ); > break; > > default : > printf("Invalid grade\n" ); > } > > may be transformed to something like > > if (grad=='A') > printf("Excellent!\n" ); > else if (grad=='B') > printf("Well done\n" ); > else > printf("Invalid grade\n" ); > ------------------------------------------------- > > Are you aware of such a transformation pass ? Thanks. > Zhoulai > _______________________________________________ > LLVM Developers mailing list > LLVMdev at cs.uiuc.edu http://llvm.cs.uiuc.edu > http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev-------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.llvm.org/pipermail/llvm-dev/attachments/20150724/fcd14acf/attachment.html>