From 87e169d05d75db5112df20361de33f7398ef27d5 Mon Sep 17 00:00:00 2001
From: "W. Felix Handte" <w@felixhandte.com>
Date: Fri, 20 Jan 2023 17:32:49 -0500
Subject: [PATCH 1/2] Add Additional Flags to PGO Build

In GCC, we can add a couple more flags to give us confidence that the profile
data is actually being found and used.

Also, my system for example doesn't have a binary installed under the name
`llvm-profdata`, but it does have, e.g., `llvm-profdata-13`, etc. So this
commit adds a variable that can be overridden.
---
 programs/Makefile | 9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/programs/Makefile b/programs/Makefile
index b79b60b4fb2..fcff41dc1b3 100644
--- a/programs/Makefile
+++ b/programs/Makefile
@@ -231,9 +231,12 @@ zstd-dll : zstd
 
 ## zstd-pgo: zstd executable optimized with PGO.
 .PHONY: zstd-pgo
+zstd-pgo : LLVM_PROFDATA?=llvm-profdata
+zstd-pgo : PROF_GENERATE_FLAGS=-fprofile-generate $(if $(findstring gcc,$(CC)),-fprofile-dir=.)
+zstd-pgo : PROF_USE_FLAGS=-fprofile-use $(if $(findstring gcc,$(CC)),-fprofile-dir=. -Werror=missing-profile -Wno-error=coverage-mismatch)
 zstd-pgo :
 	$(MAKE) clean HASH_DIR=$(HASH_DIR)
-	$(MAKE) zstd HASH_DIR=$(HASH_DIR) MOREFLAGS=-fprofile-generate
+	$(MAKE) zstd HASH_DIR=$(HASH_DIR) MOREFLAGS="$(PROF_GENERATE_FLAGS)"
 	./zstd -b19i1 $(PROFILE_WITH)
 	./zstd -b16i1 $(PROFILE_WITH)
 	./zstd -b9i2 $(PROFILE_WITH)
@@ -245,8 +248,8 @@ ifndef BUILD_DIR
 else
 	$(RM) zstd $(BUILD_DIR)/zstd $(BUILD_DIR)/*.o
 endif
-	case $(CC) in *clang*) if ! [ -e default.profdata ]; then llvm-profdata merge -output=default.profdata default*.profraw; fi ;; esac
-	$(MAKE) zstd HASH_DIR=$(HASH_DIR) MOREFLAGS=-fprofile-use
+	case $(CC) in *clang*) if ! [ -e default.profdata ]; then $(LLVM_PROFDATA) merge -output=default.profdata default*.profraw; fi ;; esac
+	$(MAKE) zstd HASH_DIR=$(HASH_DIR) MOREFLAGS="$(PROF_USE_FLAGS)"
 
 ## zstd-small: minimal target, supporting only zstd compression and decompression. no bench. no legacy. no other format.
 CLEAN += zstd-small zstd-frugal

From aab3dd4312d98b2eff868012a50b1523f41a1a9a Mon Sep 17 00:00:00 2001
From: "W. Felix Handte" <w@felixhandte.com>
Date: Fri, 20 Jan 2023 17:36:24 -0500
Subject: [PATCH 2/2] Add PGO Build Jobs to CI

---
 .github/workflows/dev-short-tests.yml | 23 +++++++++++++++++++++++
 1 file changed, 23 insertions(+)

diff --git a/.github/workflows/dev-short-tests.yml b/.github/workflows/dev-short-tests.yml
index 5a29789f907..3f6675f0d73 100644
--- a/.github/workflows/dev-short-tests.yml
+++ b/.github/workflows/dev-short-tests.yml
@@ -500,6 +500,29 @@ jobs:
       run: |
         make clangbuild
 
+  clang-pgo:
+    runs-on: ubuntu-latest
+    steps:
+    - uses: actions/checkout@ac593985615ec2ede58e132d2e21d2b1cbd6127c # tag=v3
+    - name: Build PGO Zstd with Clang
+      env:
+        CC: clang-14
+        LLVM_PROFDATA: llvm-profdata-14
+      run: |
+        make -C programs zstd-pgo
+        ./programs/zstd -b
+
+  gcc-pgo:
+    runs-on: ubuntu-latest
+    steps:
+    - uses: actions/checkout@ac593985615ec2ede58e132d2e21d2b1cbd6127c # tag=v3
+    - name: Build PGO Zstd with GCC
+      env:
+        CC: gcc
+      run: |
+        make -C programs zstd-pgo
+        ./programs/zstd -b
+
 
 # For reference : icc tests
 # icc tests are currently failing on Github Actions, likely to issues during installation stage