[llvm] f96c1cc - [VPlan] Add `-vplan-print-after=` option (#178700)

[via llvm-commits]

Author: Andrei Elovikov
Date: 2026-02-10T16:07:25Z
New Revision: f96c1ccc1e8c0d1ea0ded762a7d0e0d933770ea2

URL: https://github.com/llvm/llvm-project/commit/f96c1ccc1e8c0d1ea0ded762a7d0e0d933770ea2
DIFF: https://github.com/llvm/llvm-project/commit/f96c1ccc1e8c0d1ea0ded762a7d0e0d933770ea2.diff

LOG: [VPlan] Add `-vplan-print-after=` option (#178700)

UpdateTestChecks support is updated in subsequent
https://github.com/llvm/llvm-project/pull/178736.

Added: 
    llvm/test/Transforms/LoopVectorize/vplan-print-after.ll

Modified: 
    llvm/lib/Transforms/Vectorize/LoopVectorize.cpp
    llvm/lib/Transforms/Vectorize/VPlanTransforms.h

Removed: 
    


################################################################################
diff  --git a/llvm/lib/Transforms/Vectorize/LoopVectorize.cpp b/llvm/lib/Transforms/Vectorize/LoopVectorize.cpp
index b5978c670dd94..5404e98bae14f 100644
--- a/llvm/lib/Transforms/Vectorize/LoopVectorize.cpp
+++ b/llvm/lib/Transforms/Vectorize/LoopVectorize.cpp
@@ -367,9 +367,13 @@ cl::opt<bool>
                           cl::desc("Verfiy VPlans after VPlan transforms."));
 
 #if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
-cl::opt<bool> llvm::PrintAfterEachVPlanPass(
+cl::opt<bool> llvm::VPlanPrintAfterAll(
     "vplan-print-after-all", cl::init(false), cl::Hidden,
-    cl::desc("Print after each VPlanTransforms::runPass."));
+    cl::desc("Print VPlans after all VPlan transformations."));
+
+cl::list<std::string> llvm::VPlanPrintAfterPasses(
+    "vplan-print-after", cl::Hidden,
+    cl::desc("Print VPlans after specified VPlan transformations (regexp)."));
 #endif
 
 // This flag enables the stress testing of the VPlan H-CFG construction in the

diff  --git a/llvm/lib/Transforms/Vectorize/VPlanTransforms.h b/llvm/lib/Transforms/Vectorize/VPlanTransforms.h
index dec8b4fd6a1d8..07ad08aef471f 100644
--- a/llvm/lib/Transforms/Vectorize/VPlanTransforms.h
+++ b/llvm/lib/Transforms/Vectorize/VPlanTransforms.h
@@ -19,6 +19,7 @@
 #include "llvm/ADT/ScopeExit.h"
 #include "llvm/Support/CommandLine.h"
 #include "llvm/Support/Compiler.h"
+#include "llvm/Support/Regex.h"
 
 namespace llvm {
 
@@ -38,7 +39,8 @@ LLVM_ABI_FOR_TEST extern cl::opt<bool> VerifyEachVPlan;
 LLVM_ABI_FOR_TEST extern cl::opt<bool> EnableWideActiveLaneMask;
 
 #if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
-LLVM_ABI_FOR_TEST extern cl::opt<bool> PrintAfterEachVPlanPass;
+LLVM_ABI_FOR_TEST extern cl::opt<bool> VPlanPrintAfterAll;
+LLVM_ABI_FOR_TEST extern cl::list<std::string> VPlanPrintAfterPasses;
 #endif
 
 struct VPlanTransforms {
@@ -52,7 +54,11 @@ struct VPlanTransforms {
 #if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
       // Make sure to print before verification, so that output is more useful
       // in case of failures:
-      if (PrintAfterEachVPlanPass) {
+      if (VPlanPrintAfterAll ||
+          (VPlanPrintAfterPasses.getNumOccurrences() > 0 &&
+           any_of(VPlanPrintAfterPasses, [PassName](StringRef Entry) {
+             return Regex(Entry).match(PassName);
+           }))) {
         dbgs() << "VPlan after " << PassName << '\n';
         dbgs() << Plan << '\n';
       }

diff  --git a/llvm/test/Transforms/LoopVectorize/vplan-print-after.ll b/llvm/test/Transforms/LoopVectorize/vplan-print-after.ll
new file mode 100644
index 0000000000000..8014a4e480d65
--- /dev/null
+++ b/llvm/test/Transforms/LoopVectorize/vplan-print-after.ll
@@ -0,0 +1,29 @@
+; RUN: opt -passes=loop-vectorize -disable-output  -force-vector-width=4  < %s \
+; RUN:   -vplan-print-after=simplify -vplan-print-after=printFinalVPlan \
+; RUN:   2>&1 | FileCheck %s --implicit-check-not "VPlan after"
+; REQUIRES: asserts
+
+; CHECK:      VPlan after simplifyRecipes
+; CHECK-NEXT: VPlan 'Initial VPlan for VF={4},UF>=1' {
+; CHECK:      VPlan after simplifyBlends
+; CHECK-NEXT: VPlan 'Initial VPlan for VF={4},UF>=1' {
+; CHECK:      VPlan after simplifyRecipes
+; CHECK-NEXT: VPlan 'Initial VPlan for VF={4},UF>=1' {
+; CHECK:      VPlan after printFinalVPlan
+; CHECK-NEXT: VPlan 'Final VPlan for VF={4},UF={1}' {
+
+define void @foo(ptr %ptr, i64 %n) {
+entry:
+  br label %header
+
+header:
+  %iv = phi i64 [ 0, %entry ], [ %iv.next, %header ]
+  %gep = getelementptr i64, ptr %ptr, i64 %iv
+  store i64 %iv, ptr %gep
+  %iv.next = add nsw i64 %iv, 1
+  %exitcond = icmp slt i64 %iv.next, %n
+  br i1 %exitcond, label %header, label %exit
+
+exit:
+  ret void
+}