[MBP] Use Function::optForSize() instead of checking OptimizeForSize directly.

[haicheng]

Summary

Fix a FIXME. Disable loop alignment if compiled with -Oz now.

[iteratee]

This looks fine. Thanks for fixing it.

[haicheng]

Committed in r268121. Thank you, Kyle.

lib/CodeGen/MachineBlockPlacement.cpp

 }
 
 void MachineBlockPlacement::alignBlocks(MachineFunction &F) {
   // Walk through the backedges of the function now that we have fully laid out
   // the basic blocks and align the destination of each backedge. We don't rely
   // exclusively on the loop info here so that we can align backedges in
   // unnatural CFGs and backedges that were introduced purely because of the
   // loop rotations done during this layout pass.
-  // FIXME: Use Function::optForSize().
-  if (F.getFunction()->hasFnAttribute(Attribute::OptimizeForSize))
+  if (F.getFunction()->optForSize())
     return;
   BlockChain &FunctionChain = *BlockToChain[&F.front()];
   if (FunctionChain.begin() == FunctionChain.end())
     return; // Empty chain.
 
   const BranchProbability ColdProb(1, 5); // 20%
   BlockFrequency EntryFreq = MBFI->getBlockFreq(&F.front());
   BlockFrequency WeightedEntryFreq = EntryFreq * ColdProb;

test/CodeGen/PowerPC/code-align.ll

for.body:                                         ; preds = %for.body, %entry
   %indvars.iv.next = add nuw nsw i64 %indvars.iv, 1
   %exitcond = icmp eq i64 %indvars.iv.next, 2048
   br i1 %exitcond, label %for.end, label %for.body
 
 for.end:                                          ; preds = %for.body
   ret void
 }
 
+; Function Attrs: nounwind
+define void @test_minsize(i32 signext %x, i32* nocapture %a) #2 {
+entry:
+  br label %vector.body
+
+; GENERIC-LABEL: @test_minsize
+; BASIC-LABEL: @test_minsize
+; PWR-LABEL: @test_minsize
+; GENERIC: mtctr
+; BASIC: mtctr
+; PWR: mtctr
+; GENERIC-NOT: .p2align
+; BASIC-NOT: .p2align
+; PWR-NOT: .p2align
+; GENERIC: lwzu
+; BASIC: lwzu
+; PWR: lwzu
+; GENERIC: bdnz
+; BASIC: bdnz
+; PWR: bdnz
+
+vector.body:                                      ; preds = %vector.body, %entry
+  %index = phi i64 [ 0, %entry ], [ %index.next, %vector.body ]
+  %induction45 = or i64 %index, 1
+  %0 = getelementptr inbounds i32, i32* %a, i64 %index
+  %1 = getelementptr inbounds i32, i32* %a, i64 %induction45
+  %2 = load i32, i32* %0, align 4
+  %3 = load i32, i32* %1, align 4
+  %4 = add nsw i32 %2, 4
+  %5 = add nsw i32 %3, 4
+  %6 = mul nsw i32 %4, 3
+  %7 = mul nsw i32 %5, 3
+  store i32 %6, i32* %0, align 4
+  store i32 %7, i32* %1, align 4
+  %index.next = add i64 %index, 2
+  %8 = icmp eq i64 %index.next, 2048
+  br i1 %8, label %for.end, label %vector.body
+
+for.end:                                          ; preds = %vector.body
+  ret void
+}
 attributes #0 = { nounwind readnone }
 attributes #1 = { nounwind }
+attributes #2 = { nounwind minsize}
 

test/CodeGen/X86/loop-blocks.ll

block101:
   call void @bar101()
   br label %loop
 
 block102:
   call void @bar102()
   br label %loop
 }
 
+; CHECK-LABEL: check_minsize:
+;      CHECK:   jmp   .LBB4_1
+; CHECK-NOT:   align
+; CHECK-NEXT: .LBB4_2:
+; CHECK-NEXT:   callq loop_latch
+; CHECK-NEXT: .LBB4_1:
+; CHECK-NEXT:   callq loop_header
+
+
+define void @check_minsize() minsize nounwind {
+entry:
+  br label %loop
+
+loop:
+  call void @loop_header()
+  %t0 = tail call i32 @get()
+  %t1 = icmp slt i32 %t0, 0
+  br i1 %t1, label %done, label %bb
+
+bb:
+  call void @loop_latch()
+  br label %loop
+
+done:
+  call void @exit()
+  ret void
+}
+
 declare void @bar99() nounwind
 declare void @bar100() nounwind
 declare void @bar101() nounwind
 declare void @bar102() nounwind
 declare void @body() nounwind
 declare void @exit() nounwind
 declare void @loop_header() nounwind
 declare void @loop_latch() nounwind
 declare i32 @get() nounwind
 declare void @block_a_true_func() nounwind
 declare void @block_a_false_func() nounwind
 declare void @block_a_merge_func() nounwind