[llvm] 7543436 - [AArch64] [FrameLowering] Allow conditional insertion of CFI instruction

[David Tellenbach via llvm-commits]

Author: David Tellenbach
Date: 2019-11-22T00:27:41+01:00
New Revision: 75434366cec161ee532ee0ec3dcb5ebeb588d9df

URL: https://github.com/llvm/llvm-project/commit/75434366cec161ee532ee0ec3dcb5ebeb588d9df
DIFF: https://github.com/llvm/llvm-project/commit/75434366cec161ee532ee0ec3dcb5ebeb588d9df.diff

LOG: [AArch64] [FrameLowering] Allow conditional insertion of CFI instruction

Summary:
The insertion of most CFI instructions during AArch64 frame lowering can
be disabled (e.g. using the function attribute `nounwind`).

This patch enables conditional insertion for one more CFI instruction.

Reviewers: t.p.northover, ostannard

Reviewed By: ostannard

Subscribers: kristof.beyls, hiraditya, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D70129

Added: 
    llvm/test/CodeGen/AArch64/no_cfi.ll

Modified: 
    llvm/lib/Target/AArch64/AArch64FrameLowering.cpp
    llvm/test/CodeGen/AArch64/arm64-blockaddress.ll

Removed: 
    


################################################################################
diff  --git a/llvm/lib/Target/AArch64/AArch64FrameLowering.cpp b/llvm/lib/Target/AArch64/AArch64FrameLowering.cpp
index 970d7802b1d1..eca9b1e75c2a 100644
--- a/llvm/lib/Target/AArch64/AArch64FrameLowering.cpp
+++ b/llvm/lib/Target/AArch64/AArch64FrameLowering.cpp
@@ -935,15 +935,15 @@ void AArch64FrameLowering::emitPrologue(MachineFunction &MF,
       emitFrameOffset(MBB, MBBI, DL, AArch64::SP, AArch64::SP,
                       {-NumBytes, MVT::i8}, TII, MachineInstr::FrameSetup,
                       false, NeedsWinCFI, &HasWinCFI);
-      if (!NeedsWinCFI) {
+      if (!NeedsWinCFI && needsFrameMoves) {
         // Label used to tie together the PROLOG_LABEL and the MachineMoves.
         MCSymbol *FrameLabel = MMI.getContext().createTempSymbol();
-        // Encode the stack size of the leaf function.
-        unsigned CFIIndex = MF.addFrameInst(
-            MCCFIInstruction::createDefCfaOffset(FrameLabel, -NumBytes));
-        BuildMI(MBB, MBBI, DL, TII->get(TargetOpcode::CFI_INSTRUCTION))
-            .addCFIIndex(CFIIndex)
-            .setMIFlags(MachineInstr::FrameSetup);
+          // Encode the stack size of the leaf function.
+          unsigned CFIIndex = MF.addFrameInst(
+              MCCFIInstruction::createDefCfaOffset(FrameLabel, -NumBytes));
+          BuildMI(MBB, MBBI, DL, TII->get(TargetOpcode::CFI_INSTRUCTION))
+              .addCFIIndex(CFIIndex)
+              .setMIFlags(MachineInstr::FrameSetup);
       }
     }
 

diff  --git a/llvm/test/CodeGen/AArch64/arm64-blockaddress.ll b/llvm/test/CodeGen/AArch64/arm64-blockaddress.ll
index b50ffdef5ddd..b35cb28b4726 100644
--- a/llvm/test/CodeGen/AArch64/arm64-blockaddress.ll
+++ b/llvm/test/CodeGen/AArch64/arm64-blockaddress.ll
@@ -7,12 +7,12 @@
 define i64 @t() nounwind ssp {
 entry:
 ; CHECK-LABEL: t:
-; CHECK: adrp [[REG:x[0-9]+]], Ltmp1 at PAGE
-; CHECK: add {{x[0-9]+}}, [[REG]], Ltmp1 at PAGEOFF
+; CHECK: adrp [[REG:x[0-9]+]], Ltmp0 at PAGE
+; CHECK: add {{x[0-9]+}}, [[REG]], Ltmp0 at PAGEOFF
 
 ; CHECK-LINUX-LABEL: t:
-; CHECK-LINUX: adrp [[REG:x[0-9]+]], .Ltmp1
-; CHECK-LINUX: add {{x[0-9]+}}, [[REG]], :lo12:.Ltmp1
+; CHECK-LINUX: adrp [[REG:x[0-9]+]], .Ltmp0
+; CHECK-LINUX: add {{x[0-9]+}}, [[REG]], :lo12:.Ltmp0
 
 ; CHECK-LARGE-LABEL: t:
 ; CHECK-LARGE: movz [[ADDR_REG:x[0-9]+]], #:abs_g0_nc:[[DEST_LBL:.Ltmp[0-9]+]]

diff  --git a/llvm/test/CodeGen/AArch64/no_cfi.ll b/llvm/test/CodeGen/AArch64/no_cfi.ll
new file mode 100644
index 000000000000..49e34b3c5e11
--- /dev/null
+++ b/llvm/test/CodeGen/AArch64/no_cfi.ll
@@ -0,0 +1,13 @@
+; RUN: llc -mtriple aarch64-arm-linux-gnu -o - %s | FileCheck %s
+
+; CHECK:        a:                                      // @a
+; CHECK-NEXT:   // %bb.0:
+; CHECK-NEXT:           sub     sp, sp, #16
+; CHECK-NOT:            .cfi{{.*}}
+; CHECK:                ret
+define void @a() nounwind {
+  %1 = alloca i32, align 4
+  store i32 1, i32* %1, align 4
+  ret void
+}
+