[CodeGen] Allow -enable-ext-tsp-block-placement and -apply-ext-tsp-for-size passed together

llvm/lib/CodeGen/MachineBlockPlacement.cpp

@@ -3598,10 +3598,10 @@ bool MachineBlockPlacement::run(MachineFunction &MF) {
   bool UseExtTspForPerf = false;
   bool UseExtTspForSize = false;
   if (3 <= MF.size() && MF.size() <= ExtTspBlockPlacementMaxBlocks) {
+    UseExtTspForSize = OptForSize && ApplyExtTspForSize;
     UseExtTspForPerf =
-        EnableExtTspBlockPlacement &&
+        !UseExtTspForSize && EnableExtTspBlockPlacement &&
         (ApplyExtTspWithoutProfile || MF.getFunction().hasProfileData());
-    UseExtTspForSize = OptForSize && ApplyExtTspForSize;
   }
 
   // Apply tail duplication.

llvm/test/CodeGen/X86/code_placement_ext_tsp_size_and_perf.ll

@@ -0,0 +1,91 @@
+; RUN: llc -mcpu=corei7 -mtriple=x86_64-linux -verify-machineinstrs -enable-ext-tsp-block-placement -apply-ext-tsp-for-size < %s | FileCheck %s
+
+;; Cold function with optsize: should use ext-tsp for size.
+;; The size-optimized layout keeps the original order (b0, b1, b2) since it
+;; minimizes code size by avoiding extra jumps.
+define void @cold_func() optsize !prof !2 {
+;
+; +-----+
+; | b0  | -+
+; +-----+  |
+;   |      |
+;   | 10   |
+;   v      |
+; +-----+  |
+; | b1  |  | 10000
+; +-----+  |
+;   |      |
+;   | 10   |
+;   v      |
+; +-----+  |
+; | b2  | <+
+; +-----+
+;
+; CHECK-LABEL: cold_func:
+; CHECK: %b0
+; CHECK: %b1
+; CHECK: %b2
+
+b0:
+  %call = call zeroext i1 @a()
+  br i1 %call, label %b1, label %b2, !prof !1
+
+b1:
+  call void @d()
+  call void @d()
+  call void @d()
+  br label %b2
+
+b2:
+  call void @e()
+  ret void
+}
+
+;; Hot function without optsize: should use ext-tsp for perf.
+;; The perf-optimized layout reorders blocks to place the most likely successor
+;; (b2) right after b0, giving b0 -> b2 -> b1.
+define void @hot_func() !prof !3 {
+;
+; +-----+
+; | b0  | -+
+; +-----+  |
+;   |      |
+;   | 40   |
+;   v      |
+; +-----+  |
+; | b1  |  | 100
+; +-----+  |
+;   |      |
+;   | 40   |
+;   v      |
+; +-----+  |
+; | b2  | <+
+; +-----+
+;
+; CHECK-LABEL: hot_func:
+; CHECK: %b0
+; CHECK: %b2
+; CHECK: %b1
+
+b0:
+  %call = call zeroext i1 @a()
+  br i1 %call, label %b1, label %b2, !prof !1
+
+b1:
+  call void @d()
+  call void @d()
+  call void @d()
+  br label %b2
+
+b2:
+  call void @e()
+  ret void
+}
+
+declare zeroext i1 @a()
+declare void @d()
+declare void @e()
+
+!1 = !{!"branch_weights", i32 10, i32 10000}
+!2 = !{!"function_entry_count", i64 1}
+!3 = !{!"function_entry_count", i64 2200}