indvars: Added DisableIVRewrite and WidenIVs.
This adds functionality to remove size/zero extension during indvars
without generating a canonical IV and rewriting all IV users. It's
disabled by default so should have no effect on codegen. Work in progress.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@130829 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Analysis/IVUsers.cpp b/lib/Analysis/IVUsers.cpp
index 2cda791..a8fe545 100644
--- a/lib/Analysis/IVUsers.cpp
+++ b/lib/Analysis/IVUsers.cpp
@@ -21,6 +21,7 @@
#include "llvm/Analysis/Dominators.h"
#include "llvm/Analysis/LoopPass.h"
#include "llvm/Analysis/ScalarEvolutionExpressions.h"
+#include "llvm/Support/CommandLine.h"
#include "llvm/Target/TargetData.h"
#include "llvm/Assembly/Writer.h"
#include "llvm/ADT/STLExtras.h"
@@ -38,6 +39,15 @@
INITIALIZE_PASS_END(IVUsers, "iv-users",
"Induction Variable Users", false, true)
+// IVUsers behavior currently depends on this temporary indvars mode. The
+// option must be defined upstream from its uses.
+namespace llvm {
+ bool DisableIVRewrite = false;
+}
+cl::opt<bool, true> DisableIVRewriteOpt(
+ "disable-iv-rewrite", cl::Hidden, cl::location(llvm::DisableIVRewrite),
+ cl::desc("Disable canonical induction variable rewriting"));
+
Pass *llvm::createIVUsersPass() {
return new IVUsers();
}
@@ -90,6 +100,11 @@
if (Width > 64 || (TD && !TD->isLegalInteger(Width)))
return false;
+ // We expect Sign/Zero extension to be eliminated from the IR before analyzing
+ // any downstream uses.
+ if (DisableIVRewrite && (isa<SExtInst>(I) || isa<ZExtInst>(I)))
+ return false;
+
if (!Processed.insert(I))
return true; // Instruction already handled.