[Profile] Propagate branch metadata properly in InstCombine

[davidxl]

Summary

More test cases are also added to cover cases that are currently working.

[davidxl]

Updated the patch to fix more bugs in inst-combine that drops profile meta data.

[spatel]

lib/Transforms/InstCombine/InstCombineSelect.cpp

416

"SwapBranchWeights" -> "swapBranchWeights"

On 2nd thought, can we refactor/reuse copyMetadata() from LoopUnswitch.cpp instead of duplicating?

[davidxl]

lib/Transforms/InstCombine/InstCombineSelect.cpp

416

Refactored the APIs.

[davidxl]

Patch updated using new meta data API.

[spatel]

In D23590#523224, @davidxl wrote:

Patch updated using new meta data API.

LGTM. Thanks!

lib/Transforms/InstCombine/InstCombineSelect.cpp

       // TODO: The one-use restrictions for a scalar select could be eased if
       // the fold of a select in visitLoadInst() was enhanced to match a pattern
       // that includes a cast.
       return nullptr;
     }
 
     // Fold this by inserting a select from the input values.
     Value *NewSI = Builder->CreateSelect(SI.getCondition(), TI->getOperand(0),
-                                         FI->getOperand(0), SI.getName()+".v");
+                                         FI->getOperand(0), SI.getName()+".v", &SI);
     return CastInst::Create(Instruction::CastOps(TI->getOpcode()), NewSI,
                             TI->getType());
   }
 
   // TODO: This function ends awkwardly in unreachable - fix to be more normal.
 
   // Only handle binary operators with one-use here. As with the cast case
   // above, it may be possible to relax the one-use constraint, but that needs

     OtherOpF = FI->getOperand(1);
     MatchIsOpZero = true;
   } else {
     return nullptr;
   }
 
   // If we reach here, they do have operations in common.
   Value *NewSI = Builder->CreateSelect(SI.getCondition(), OtherOpT,
-                                       OtherOpF, SI.getName()+".v");
+                                       OtherOpF, SI.getName()+".v", &SI);
 
   if (BinaryOperator *BO = dyn_cast<BinaryOperator>(TI)) {
     if (MatchIsOpZero)
       return BinaryOperator::Create(BO->getOpcode(), MatchOp, NewSI);
     else
       return BinaryOperator::Create(BO->getOpcode(), NewSI, MatchOp);
   }
   llvm_unreachable("Shouldn't get here");

 }
 
 /// We want to turn:
 ///   (select (icmp eq (and X, C1), 0), Y, (or Y, C2))
 /// into:
 ///   (or (shl (and X, C1), C3), y)
 /// iff:
 ///   C1 and C2 are both powers of 2
 /// where:

test/Transforms/InstCombine/select_meta.ll

+; RUN: opt < %s -instcombine -S | FileCheck %s
+
+define i32 @foo(i32) local_unnamed_addr #0  {
+  %2 = icmp sgt i32 %0, 2
+  %3 = add nsw i32 %0, 20
+  %4 = add nsw i32 %0, -20
+  select i1 %2, i32 %3, i32 %4, !prof !1
+  ret i32 %5
+; CHECK-LABEL: @foo
+; CHECK: select {{.*}}, !prof ![[MD1:[0-9]+]]
+}
+
+
+; SMAX(SMAX(x, y), x) -> SMAX(x, y)
+define i32 @test30(i32 %x, i32 %y) {
+  %cmp = icmp sgt i32 %x, %y
+  %cond = select i1 %cmp, i32 %x, i32 %y, !prof !1
+  %cmp5 = icmp sgt i32 %cond, %x
+  %retval = select i1 %cmp5, i32 %cond, i32 %x, !prof !2
+  ret i32 %retval
+; CHECK-LABEL: @test30
+; CHECK: select {{.*}}, !prof ![[MD1]]
+}
+
+define i32 @test70(i32 %x) {
+entry:
+  %cmp = icmp slt i32 %x, 75
+  %cond = select i1 %cmp, i32 75, i32 %x, !prof !1
+  %cmp3 = icmp slt i32 %cond, 36
+  %retval = select i1 %cmp3, i32 36, i32 %cond, !prof !2
+  ret i32 %retval
+; CHECK-LABEL: @test70
+; CHECK: select {{.*}}, !prof ![[MD1]]
+}
+
+
+; SMIN(SMIN(X, 92), 11) -> SMIN(X, 11)
+define i32 @test72(i32 %x) {
+  %cmp = icmp sgt i32 %x, 92
+  %cond = select i1 %cmp, i32 92, i32 %x, !prof !1
+  %cmp3 = icmp sgt i32 %cond, 11
+  %retval = select i1 %cmp3, i32 11, i32 %cond, !prof !2
+  ret i32 %retval
+; CHECK-LABEL: @test72
+; CHECK: select {{.*}}, !prof ![[MD2:[0-9]+]]
+}
+
+
+; SMAX(SMAX(X, 36), 75) -> SMAX(X, 75)
+define i32 @test74(i32 %x) {
+  %cmp = icmp slt i32 %x, 36
+  %cond = select i1 %cmp, i32 36, i32 %x, !prof !1
+  %cmp3 = icmp slt i32 %cond, 75
+  %retval = select i1 %cmp3, i32 75, i32 %cond, !prof !2
+  ret i32 %retval
+; CHECK-LABEL: @test74
+; CHECK: select {{.*}}, !prof ![[MD2]]
+}
+
+define void @min_max_bitcast(<4 x float> %a, <4 x float> %b, <4 x i32>* %ptr1, <4 x i32>* %ptr2) {
+  %cmp = fcmp olt <4 x float> %a, %b
+  %bc1 = bitcast <4 x float> %a to <4 x i32>
+  %bc2 = bitcast <4 x float> %b to <4 x i32>
+  %sel1 = select <4 x i1> %cmp, <4 x i32> %bc1, <4 x i32> %bc2, !prof !1
+  %sel2 = select <4 x i1> %cmp, <4 x i32> %bc2, <4 x i32> %bc1, !prof !1
+  store <4 x i32> %sel1, <4 x i32>* %ptr1
+  store <4 x i32> %sel2, <4 x i32>* %ptr2
+  ret void
+; CHECK-LABEL: @min_max_bitcast
+; CHECK: select {{.*}}, !prof ![[MD1]]
+}
+
+!1 = !{!"branch_weights", i32 2, i32 10}
+!2 = !{!"branch_weights", i32 3, i32 10}
+
+; CHECK: ![[MD1]] = !{!"branch_weights", i32 2, i32 10}
+; CHECK: ![[MD2]] = !{!"branch_weights", i32 3, i32 10}
+