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Check InlineAsm clobbers in PPCCTRLoops

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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.

llvm-svn: 182191
This commit is contained in:
Hal Finkel 2013-05-18 09:20:39 +00:00
parent 5256d08973
commit d4eb9291fa
2 changed files with 53 additions and 0 deletions
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15
lib/Target/PowerPC/PPCCTRLoops.cpp
View File

@ -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 Triple &TT, BasicBlock *BB) {
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();

38
test/CodeGen/PowerPC/ctrloop-asm.ll Normal file
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@ -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
}