From 269b335bd7332cd0d13451260d408dc9fcbcb5b1 Mon Sep 17 00:00:00 2001
From: Arthur Eubanks <aeubanks@google.com>
Date: Sat, 10 Apr 2021 11:59:04 -0700
Subject: [PATCH] [Inliner] Propagate SROA analysis through invariant group
 intrinsics

SROA can handle invariant group intrinsics, let the inliner know that
for better heuristics when the intrinsics are present.

This fixes size issues in a couple files when turning on
-fstrict-vtable-pointers in Chrome.

Reviewed By: rnk, mtrofin

Differential Revision: https://reviews.llvm.org/D100249
---
 llvm/lib/Analysis/InlineCost.cpp                   |  5 +++++
 .../test/Transforms/Inline/invariant-group-sroa.ll | 26 ++++++++++++++++++++++
 2 files changed, 31 insertions(+)
 create mode 100644 llvm/test/Transforms/Inline/invariant-group-sroa.ll

diff --git a/llvm/lib/Analysis/InlineCost.cpp b/llvm/lib/Analysis/InlineCost.cpp
index 06cc778..b367efa 100644
--- a/llvm/lib/Analysis/InlineCost.cpp
+++ b/llvm/lib/Analysis/InlineCost.cpp
@@ -1884,6 +1884,11 @@ bool CallAnalyzer::visitCallBase(CallBase &Call) {
     case Intrinsic::vastart:
       InitsVargArgs = true;
       return false;
+    case Intrinsic::launder_invariant_group:
+    case Intrinsic::strip_invariant_group:
+      if (auto *SROAArg = getSROAArgForValueOrNull(II->getOperand(0)))
+        SROAArgValues[II] = SROAArg;
+      return true;
     }
   }
 
diff --git a/llvm/test/Transforms/Inline/invariant-group-sroa.ll b/llvm/test/Transforms/Inline/invariant-group-sroa.ll
new file mode 100644
index 0000000..086e8b6
--- /dev/null
+++ b/llvm/test/Transforms/Inline/invariant-group-sroa.ll
@@ -0,0 +1,26 @@
+; RUN: opt -passes='print<inline-cost>' -disable-output %s 2>&1 | FileCheck %s
+
+; SROA analysis should yield non-zero savings for allocas passed through invariant group intrinsics
+; CHECK: SROACostSavings: 10
+
+declare i8* @llvm.launder.invariant.group.p0i8(i8*)
+declare i8* @llvm.strip.invariant.group.p0i8(i8*)
+
+declare void @b()
+
+define i32 @f() {
+  %a = alloca i32
+  %r = call i32 @g(i32* %a)
+  ret i32 %r
+}
+
+define i32 @g(i32* %a) {
+  %a_i8 = bitcast i32* %a to i8*
+  %a_inv_i8 = call i8* @llvm.launder.invariant.group.p0i8(i8* %a_i8)
+  %a_inv = bitcast i8* %a_inv_i8 to i32*
+  %i1 = load i32, i32* %a_inv
+  %i2 = load i32, i32* %a_inv
+  %i3 = add i32 %i1, %i2
+  %t = call i8* @llvm.strip.invariant.group.p0i8(i8* %a_inv_i8)
+  ret i32 %i3
+}
-- 
2.7.4