[llvm] 228aecb - [llvm][AArch64] Copy all operands when expanding BLR_BTI bundle (#78267)

[via llvm-commits]

Author: David Spickett
Date: 2024-01-19T11:22:43Z
New Revision: 228aecbcf106a50c30b1f8f1915d61850860cbcd

URL: https://github.com/llvm/llvm-project/commit/228aecbcf106a50c30b1f8f1915d61850860cbcd
DIFF: https://github.com/llvm/llvm-project/commit/228aecbcf106a50c30b1f8f1915d61850860cbcd.diff

LOG: [llvm][AArch64] Copy all operands when expanding BLR_BTI bundle (#78267)

Fixes #77915

Previously I based the operand copying on expandCALL_RVMARKER but did
not understand it properly at the time. This lead to me dropping the
arguments of the function being branched to.

This fixes that by copying all operands from the BLR_BTI to the BL/BLR
without skipping anything.

I've updated the existing test by adding function arguments.

Added: 
    llvm/test/CodeGen/AArch64/blr-bti-preserves-operands.mir

Modified: 
    llvm/lib/Target/AArch64/AArch64ExpandPseudoInsts.cpp

Removed: 
    llvm/test/CodeGen/AArch64/blr-bti-preserves-regmask.mir


################################################################################
diff  --git a/llvm/lib/Target/AArch64/AArch64ExpandPseudoInsts.cpp b/llvm/lib/Target/AArch64/AArch64ExpandPseudoInsts.cpp
index bb7f4d907ffd7f2..c45cb8eba897235 100644
--- a/llvm/lib/Target/AArch64/AArch64ExpandPseudoInsts.cpp
+++ b/llvm/lib/Target/AArch64/AArch64ExpandPseudoInsts.cpp
@@ -842,9 +842,11 @@ bool AArch64ExpandPseudo::expandCALL_BTI(MachineBasicBlock &MBB,
   unsigned Opc = CallTarget.isGlobal() ? AArch64::BL : AArch64::BLR;
   MachineInstr *Call =
       BuildMI(MBB, MBBI, MI.getDebugLoc(), TII->get(Opc)).getInstr();
-  Call->addOperand(CallTarget);
+
+  for (const MachineOperand &MO : MI.operands())
+    Call->addOperand(MO);
+
   Call->setCFIType(*MBB.getParent(), MI.getCFIType());
-  Call->copyImplicitOps(*MBB.getParent(), MI);
 
   MachineInstr *BTI =
       BuildMI(MBB, MBBI, MI.getDebugLoc(), TII->get(AArch64::HINT))

diff  --git a/llvm/test/CodeGen/AArch64/blr-bti-preserves-operands.mir b/llvm/test/CodeGen/AArch64/blr-bti-preserves-operands.mir
new file mode 100644
index 000000000000000..3b2f10348bd7730
--- /dev/null
+++ b/llvm/test/CodeGen/AArch64/blr-bti-preserves-operands.mir
@@ -0,0 +1,24 @@
+# RUN: llc -mtriple=aarch64-none-linux-gnu -run-pass=aarch64-expand-pseudo -o - %s | FileCheck %s
+
+# When expanding a BLR_BTI, we should copy all the operands to the branch in the
+# bundle. Otherwise we could end up using a register after the BL which was
+# clobbered by the function that was called, or overwriting an argument to that
+# function before we make the call.
+# CHECK:    BUNDLE implicit-def $lr, implicit-def $w30, implicit-def $sp, implicit-def $wsp, implicit $x0, implicit $w1, implicit $sp {
+# CHECK:      BL @_setjmp, $x0, $w1, csr_aarch64_aapcs, implicit-def $lr, implicit $sp, implicit-def dead $lr, implicit $sp, implicit-def $sp
+# CHECK:      HINT 36
+# CHECK:    }
+
+--- |
+  define void @a() {
+    ret void
+  }
+
+  declare void @_setjmp(...)
+...
+---
+name: a
+body: |
+  bb.0:
+    BLR_BTI @_setjmp, $x0, $w1, csr_aarch64_aapcs, implicit-def dead $lr, implicit $sp, implicit-def $sp
+...

diff  --git a/llvm/test/CodeGen/AArch64/blr-bti-preserves-regmask.mir b/llvm/test/CodeGen/AArch64/blr-bti-preserves-regmask.mir
deleted file mode 100644
index 91652c6e20c8f8b..000000000000000
--- a/llvm/test/CodeGen/AArch64/blr-bti-preserves-regmask.mir
+++ /dev/null
@@ -1,23 +0,0 @@
-# RUN: llc -mtriple=aarch64-none-linux-gnu -run-pass=aarch64-expand-pseudo -o - %s | FileCheck %s
-
-# When expanding a BLR_BTI, we should keep the regmask that was attached to it.
-# Otherwise we could end up using a register after the BL which was clobbered by
-# the function that was called.
-# CHECK:    BUNDLE implicit-def $lr, implicit-def $w30, implicit-def $sp, implicit-def $wsp, implicit $sp {
-# CHECK:      BL @_setjmp, csr_aarch64_aapcs, implicit-def $lr, implicit $sp, implicit-def dead $lr, implicit $sp, implicit-def $sp
-# CHECK:      HINT 36
-# CHECK:    }
-
---- |
-  define void @a() {
-    ret void
-  }
-
-  declare void @_setjmp(...)
-...
----
-name: a
-body: |
-  bb.0:
-    BLR_BTI @_setjmp, csr_aarch64_aapcs, implicit-def dead $lr, implicit $sp, implicit-def $sp
-...