diff options
author | Amara Emerson <aemerson@apple.com> | 2018-01-24 20:35:37 +0000 |
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committer | Amara Emerson <aemerson@apple.com> | 2018-01-24 20:35:37 +0000 |
commit | 25064a712806ee3610fefc90931e469030b88869 (patch) | |
tree | e92a68a18526a52e66f76d2d4d99de96eefcb6c0 | |
parent | 542b076346ab211d7783b195509ed541e9405f65 (diff) |
[AArch64][GlobalISel] Fall back during AArch64 isel if we have a volatile load.
The tablegen imported patterns for sext(load(a)) don't check for single uses
of the load or delete the original after matching. As a result two loads are
left in the generated code. This particular issue will be fixed by adding
support for a G_SEXTLOAD opcode in future.
There are however other potential issues around this that wouldn't be fixed by
a G_SEXTLOAD, so until we have a proper solution we don't try to handle volatile
loads at all in the AArch64 selector.
Fixes/works around PR36018.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@323371 91177308-0d34-0410-b5e6-96231b3b80d8
-rw-r--r-- | lib/Target/AArch64/AArch64InstructionSelector.cpp | 6 | ||||
-rw-r--r-- | test/CodeGen/AArch64/GlobalISel/irtranslator-volatile-load-pr36018.ll | 14 |
2 files changed, 20 insertions, 0 deletions
diff --git a/lib/Target/AArch64/AArch64InstructionSelector.cpp b/lib/Target/AArch64/AArch64InstructionSelector.cpp index 392ba13d74a..34d0483c403 100644 --- a/lib/Target/AArch64/AArch64InstructionSelector.cpp +++ b/lib/Target/AArch64/AArch64InstructionSelector.cpp @@ -931,6 +931,12 @@ bool AArch64InstructionSelector::select(MachineInstr &I, return false; } + // FIXME: PR36018: Volatile loads in some cases are incorrectly selected by + // folding with an extend. Until we have a G_SEXTLOAD solution bail out if + // we hit one. + if (Opcode == TargetOpcode::G_LOAD && MemOp.isVolatile()) + return false; + const unsigned PtrReg = I.getOperand(1).getReg(); #ifndef NDEBUG const RegisterBank &PtrRB = *RBI.getRegBank(PtrReg, MRI, TRI); diff --git a/test/CodeGen/AArch64/GlobalISel/irtranslator-volatile-load-pr36018.ll b/test/CodeGen/AArch64/GlobalISel/irtranslator-volatile-load-pr36018.ll new file mode 100644 index 00000000000..9bda39c9fca --- /dev/null +++ b/test/CodeGen/AArch64/GlobalISel/irtranslator-volatile-load-pr36018.ll @@ -0,0 +1,14 @@ +; RUN: llc -O0 -mtriple=aarch64-apple-ios -o - %s | FileCheck %s + +@g = global i16 0, align 2 +declare void @bar(i32) + +; Check that only one load is generated. We fall back to +define hidden void @foo() { +; CHECK-NOT: ldrh +; CHECK: ldrsh + %1 = load volatile i16, i16* @g, align 2 + %2 = sext i16 %1 to i32 + call void @bar(i32 %2) + ret void +} |