[llvm] r335137 - [DAG] Fix and-mask folding when narrowing loads.
Nirav Dave via llvm-commits
llvm-commits at lists.llvm.org
Wed Jun 20 08:36:29 PDT 2018
Author: niravd
Date: Wed Jun 20 08:36:29 2018
New Revision: 335137
URL: http://llvm.org/viewvc/llvm-project?rev=335137&view=rev
Log:
[DAG] Fix and-mask folding when narrowing loads.
Summary:
Check that and masks are strictly smaller than implicit mask from
narrowed load.
Fixes PR37820.
Reviewers: samparker, RKSimon, nemanjai
Subscribers: hiraditya, llvm-commits
Differential Revision: https://reviews.llvm.org/D48335
Added:
llvm/trunk/test/CodeGen/X86/pr37820.ll
Modified:
llvm/trunk/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
Modified: llvm/trunk/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/SelectionDAG/DAGCombiner.cpp?rev=335137&r1=335136&r2=335137&view=diff
==============================================================================
--- llvm/trunk/lib/CodeGen/SelectionDAG/DAGCombiner.cpp (original)
+++ llvm/trunk/lib/CodeGen/SelectionDAG/DAGCombiner.cpp Wed Jun 20 08:36:29 2018
@@ -8688,8 +8688,9 @@ SDValue DAGCombiner::ReduceLoadWidth(SDN
if (ShiftMask.isMask()) {
EVT MaskedVT = EVT::getIntegerVT(*DAG.getContext(),
ShiftMask.countTrailingOnes());
- // Recompute the type.
- if (TLI.isLoadExtLegal(ExtType, N0.getValueType(), MaskedVT))
+ // If the mask is smaller, recompute the type.
+ if ((ExtVT.getSizeInBits() > MaskedVT.getSizeInBits()) &&
+ TLI.isLoadExtLegal(ExtType, N0.getValueType(), MaskedVT))
ExtVT = MaskedVT;
}
}
Added: llvm/trunk/test/CodeGen/X86/pr37820.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/CodeGen/X86/pr37820.ll?rev=335137&view=auto
==============================================================================
--- llvm/trunk/test/CodeGen/X86/pr37820.ll (added)
+++ llvm/trunk/test/CodeGen/X86/pr37820.ll Wed Jun 20 08:36:29 2018
@@ -0,0 +1,25 @@
+; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py
+; RUN: llc -mtriple=x86_64-unknown-linux-gnu %s -o - | FileCheck %s
+
+ at a = external dso_local local_unnamed_addr global i64, align 8
+ at c = external dso_local local_unnamed_addr global i64, align 8
+ at b = external dso_local local_unnamed_addr global i64, align 8
+
+; Should generate a 16-bit load
+
+define void @foo() {
+; CHECK-LABEL: foo:
+; CHECK: # %bb.0: # %entry
+; CHECK-NEXT: movzwl a+{{.*}}(%rip), %eax
+; CHECK-NEXT: movq %rax, {{.*}}(%rip)
+; CHECK-NEXT: retq
+entry:
+ %0 = load i64, i64* @a, align 8
+ %1 = load i64, i64* @c, align 8
+ %and = and i64 %1, -16384
+ %add = add nsw i64 %and, 4503359447364223024
+ %shr = lshr i64 %0, %add
+ %conv1 = and i64 %shr, 4294967295
+ store i64 %conv1, i64* @b, align 8
+ ret void
+}
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