[llvm] 1a525de - [FuncSpec] Fix missed opportunities for function specialisation
Momchil Velikov via llvm-commits
llvm-commits at lists.llvm.org
Tue Oct 25 15:34:05 PDT 2022
Author: Momchil Velikov
Date: 2022-10-25T23:19:48+01:00
New Revision: 1a525dec7f3f82275517c130cf954d525cbf5e92
URL: https://github.com/llvm/llvm-project/commit/1a525dec7f3f82275517c130cf954d525cbf5e92
DIFF: https://github.com/llvm/llvm-project/commit/1a525dec7f3f82275517c130cf954d525cbf5e92.diff
LOG: [FuncSpec] Fix missed opportunities for function specialisation
When collecting the possible constant arguments to
specialise a function the compiler will abandon the search
on the first argument that is for some reason unsuitable as
a specialisation constant. Thus, depending on the traversal
order of the functions and call sites, the compiler can end
up with a different set of possible constants, hence with
different set of specialisations.
With this patch, the compiler will skip unsuitable
constants, but nevertheless will continue searching for
more.
Reviewed By: ChuanqiXu
Differential Revision: https://reviews.llvm.org/D135867
Added:
llvm/test/Transforms/FunctionSpecialization/get-possible-constants.ll
Modified:
llvm/lib/Transforms/IPO/FunctionSpecialization.cpp
Removed:
################################################################################
diff --git a/llvm/lib/Transforms/IPO/FunctionSpecialization.cpp b/llvm/lib/Transforms/IPO/FunctionSpecialization.cpp
index 8063378f77b1b..94b36f9165cd6 100644
--- a/llvm/lib/Transforms/IPO/FunctionSpecialization.cpp
+++ b/llvm/lib/Transforms/IPO/FunctionSpecialization.cpp
@@ -731,18 +731,17 @@ class FunctionSpecializer {
auto *V = CS.getArgOperand(A->getArgNo());
if (isa<PoisonValue>(V))
- return;
+ continue;
// TrackValueOfGlobalVariable only tracks scalar global variables.
if (auto *GV = dyn_cast<GlobalVariable>(V)) {
// Check if we want to specialize on the address of non-constant
// global values.
- if (!GV->isConstant())
- if (!SpecializeOnAddresses)
- return;
+ if (!GV->isConstant() && !SpecializeOnAddresses)
+ continue;
if (!GV->getValueType()->isSingleValueType())
- return;
+ continue;
}
if (isa<Constant>(V) && (Solver.getLatticeValueFor(V).isConstant() ||
diff --git a/llvm/test/Transforms/FunctionSpecialization/get-possible-constants.ll b/llvm/test/Transforms/FunctionSpecialization/get-possible-constants.ll
new file mode 100644
index 0000000000000..a6e16ad48c72a
--- /dev/null
+++ b/llvm/test/Transforms/FunctionSpecialization/get-possible-constants.ll
@@ -0,0 +1,42 @@
+; RUN: opt -S --passes=function-specialization < %s | FileCheck %s
+define dso_local i32 @p0(i32 noundef %x) {
+entry:
+ %add = add nsw i32 %x, 1
+ ret i32 %add
+}
+
+define dso_local i32 @p1(i32 noundef %x) {
+entry:
+ %sub = add nsw i32 %x, -1
+ ret i32 %sub
+}
+
+define dso_local i32 @g0(i32 noundef %x) {
+entry:
+ %call = tail call fastcc i32 @f(i32 noundef %x, ptr noundef nonnull @p0)
+ ret i32 %call
+}
+
+define internal fastcc i32 @f(i32 noundef %x, ptr nocapture noundef readonly %p) noinline {
+entry:
+ %call = tail call i32 %p(i32 noundef %x)
+ %add = add nsw i32 %call, %x
+ ret i32 %add
+}
+
+define dso_local i32 @g1(i32 noundef %x) {
+entry:
+ %call = tail call fastcc i32 @f(i32 noundef %x, ptr noundef nonnull @p1)
+ ret i32 %call
+}
+
+define dso_local i32 @g2(i32 noundef %x) {
+entry:
+ %call = tail call fastcc i32 @f(i32 noundef %x, ptr poison)
+ ret i32 %call
+}
+
+; Check that a single argument, that cannot be used for specialisation, does not
+; prevent specialisation based on other arguments.
+; CHECK: @f.1
+; CHECK: @f.2
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