[llvm] r182191 - Check InlineAsm clobbers in PPCCTRLoops

[Hal Finkel]

Author: hfinkel
Date: Sat May 18 04:20:39 2013
New Revision: 182191

URL: http://llvm.org/viewvc/llvm-project?rev=182191&view=rev
Log:
Check InlineAsm clobbers in PPCCTRLoops

We don't need to reject all inline asm as using the counter register (most does
not). Only those that explicitly clobber the counter register need to prevent
the transformation.

Added:
    llvm/trunk/test/CodeGen/PowerPC/ctrloop-asm.ll
Modified:
    llvm/trunk/lib/Target/PowerPC/PPCCTRLoops.cpp

Modified: llvm/trunk/lib/Target/PowerPC/PPCCTRLoops.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/PowerPC/PPCCTRLoops.cpp?rev=182191&r1=182190&r2=182191&view=diff
==============================================================================
--- llvm/trunk/lib/Target/PowerPC/PPCCTRLoops.cpp (original)
+++ llvm/trunk/lib/Target/PowerPC/PPCCTRLoops.cpp Sat May 18 04:20:39 2013
@@ -33,6 +33,7 @@
 #include "llvm/Analysis/ScalarEvolutionExpander.h"
 #include "llvm/IR/Constants.h"
 #include "llvm/IR/DerivedTypes.h"
+#include "llvm/IR/InlineAsm.h"
 #include "llvm/IR/Instructions.h"
 #include "llvm/IR/IntrinsicInst.h"
 #include "llvm/IR/Module.h"
@@ -148,6 +149,20 @@ bool PPCCTRLoops::mightUseCTR(const Trip
   for (BasicBlock::iterator J = BB->begin(), JE = BB->end();
        J != JE; ++J) {
     if (CallInst *CI = dyn_cast<CallInst>(J)) {
+      if (InlineAsm *IA = dyn_cast<InlineAsm>(CI->getCalledValue())) {
+        // Inline ASM is okay, unless it clobbers the ctr register.
+        InlineAsm::ConstraintInfoVector CIV = IA->ParseConstraints();
+        for (unsigned i = 0, ie = CIV.size(); i < ie; ++i) {
+          InlineAsm::ConstraintInfo &C = CIV[i];
+          if (C.Type != InlineAsm::isInput)
+            for (unsigned j = 0, je = C.Codes.size(); j < je; ++j)
+              if (StringRef(C.Codes[j]).equals_lower("{ctr}"))
+                return true;
+        }
+
+        continue;
+      }
+
       if (!TM)
         return true;
       const TargetLowering *TLI = TM->getTargetLowering();

Added: llvm/trunk/test/CodeGen/PowerPC/ctrloop-asm.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/CodeGen/PowerPC/ctrloop-asm.ll?rev=182191&view=auto
==============================================================================
--- llvm/trunk/test/CodeGen/PowerPC/ctrloop-asm.ll (added)
+++ llvm/trunk/test/CodeGen/PowerPC/ctrloop-asm.ll Sat May 18 04:20:39 2013
@@ -0,0 +1,38 @@
+target datalayout = "E-p:64:64:64-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:64:64-f32:32:32-f64:64:64-v128:128:128-n32:64"
+target triple = "powerpc64-unknown-freebsd10.0"
+; RUN: llc < %s -march=ppc64 | FileCheck %s
+
+define void @test1(i32 %c) nounwind {
+entry:
+  br label %for.body
+
+for.body:                                         ; preds = %for.body, %entry
+  %i.01 = phi i32 [ 0, %entry ], [ %inc, %for.body ]
+  call void asm sideeffect "", "~{r5}"() nounwind
+  %inc = add nsw i32 %i.01, 1
+  %exitcond = icmp eq i32 %inc, 2048
+  br i1 %exitcond, label %for.end, label %for.body
+
+for.end:                                          ; preds = %for.body
+  ret void
+; CHECK: @test1
+; CHECK: mtctr
+}
+
+define void @test2(i32 %c) nounwind {
+entry:
+  br label %for.body
+
+for.body:                                         ; preds = %for.body, %entry
+  %i.01 = phi i32 [ 0, %entry ], [ %inc, %for.body ]
+  call void asm sideeffect "", "~{ctr}"() nounwind
+  %inc = add nsw i32 %i.01, 1
+  %exitcond = icmp eq i32 %inc, 2048
+  br i1 %exitcond, label %for.end, label %for.body
+
+for.end:                                          ; preds = %for.body
+  ret void
+; CHECK: @test2
+; CHECK-NOT: mtctr
+}
+