diff options
| -rw-r--r-- | lib/Transforms/Scalar/LICM.cpp | 5 | ||||
| -rw-r--r-- | test/Transforms/LICM/2008-07-22-LoadGlobalConstant.ll | 23 |
2 files changed, 28 insertions, 0 deletions
diff --git a/lib/Transforms/Scalar/LICM.cpp b/lib/Transforms/Scalar/LICM.cpp index f7afaf4..13440c1 100644 --- a/lib/Transforms/Scalar/LICM.cpp +++ b/lib/Transforms/Scalar/LICM.cpp @@ -370,6 +370,11 @@ bool LICM::canSinkOrHoistInst(Instruction &I) { if (LI->isVolatile()) return false; // Don't hoist volatile loads! + // Loads from constant memory are always safe to move, even if they end up + // in the same alias set as something that ends up being modified. + if (AA->pointsToConstantMemory(LI->getOperand(0))) + return true; + // Don't hoist loads which have may-aliased stores in loop. unsigned Size = 0; if (LI->getType()->isSized()) diff --git a/test/Transforms/LICM/2008-07-22-LoadGlobalConstant.ll b/test/Transforms/LICM/2008-07-22-LoadGlobalConstant.ll new file mode 100644 index 0000000..c3af29b --- /dev/null +++ b/test/Transforms/LICM/2008-07-22-LoadGlobalConstant.ll @@ -0,0 +1,23 @@ +; RUN: llvm-as < %s | opt -licm | llvm-dis | grep -A 1 entry | grep load.*@a +@a = external constant float* + +define void @test(i32 %count) { +entry: + br label %forcond + +forcond: + %i.0 = phi i32 [ 0, %entry ], [ %inc, %forbody ] + %cmp = icmp ult i32 %i.0, %count + br i1 %cmp, label %forbody, label %afterfor + +forbody: + %tmp3 = load float** @a + %arrayidx = getelementptr float* %tmp3, i32 %i.0 + %tmp7 = uitofp i32 %i.0 to float + store float %tmp7, float* %arrayidx + %inc = add i32 %i.0, 1 + br label %forcond + +afterfor: + ret void +} |