[llvm] 4f19c6a - [ARM] allow long-call codegen for armv6-M eXecute Only (XO)

[Ties Stuij via llvm-commits]

Author: Ties Stuij
Date: 2023-06-28T10:50:24+01:00
New Revision: 4f19c6a7c74238875d8568e24b0ae39716aa2091

URL: https://github.com/llvm/llvm-project/commit/4f19c6a7c74238875d8568e24b0ae39716aa2091
DIFF: https://github.com/llvm/llvm-project/commit/4f19c6a7c74238875d8568e24b0ae39716aa2091.diff

LOG: [ARM] allow long-call codegen for armv6-M eXecute Only (XO)

Recently eXecute Only (XO) codegen was also allowed for armv6-M. Previously this
was only implemented for ~armv7+, effectively if MOVW/MOVT is
available. Regarding long calls, we remove the check for MOVW/MOVT when
generating code for XO, which already was redundant as in the subtarget
initialization we already check if XO is valid for the target. And targets that
generate valid XO code should be able to handle the (wrapper globaladdress)
node.

Reviewed By: efriedma

Differential Revision: https://reviews.llvm.org/D153782

Added: 
    llvm/test/CodeGen/Thumb/thumb-execute-only-long-calls.ll

Modified: 
    llvm/lib/Target/ARM/ARMISelLowering.cpp
    llvm/test/CodeGen/ARM/large-stack.ll
    llvm/test/CodeGen/Thumb2/thumb2-execute-only-long-calls.ll

Removed: 
    


################################################################################
diff  --git a/llvm/lib/Target/ARM/ARMISelLowering.cpp b/llvm/lib/Target/ARM/ARMISelLowering.cpp
index 61743a395456c..6bffbc0435959 100644
--- a/llvm/lib/Target/ARM/ARMISelLowering.cpp
+++ b/llvm/lib/Target/ARM/ARMISelLowering.cpp
@@ -2660,13 +2660,9 @@ ARMTargetLowering::LowerCall(TargetLowering::CallLoweringInfo &CLI,
     // those, the target's already in a register, so we don't need to do
     // anything extra.
     if (isa<GlobalAddressSDNode>(Callee)) {
-      // When generating execute-only code we use movw movt pair.
-      // Currently execute-only is only available for architectures that
-      // support movw movt, so we are safe to assume that.
       if (Subtarget->genExecuteOnly()) {
-        assert(Subtarget->useMovt() &&
-               "long-calls with execute-only requires movt and movw!");
-        ++NumMovwMovt;
+        if (Subtarget->useMovt())
+          ++NumMovwMovt;
         Callee = DAG.getNode(ARMISD::Wrapper, dl, PtrVt,
                              DAG.getTargetGlobalAddress(GVal, dl, PtrVt));
       } else {
@@ -2685,13 +2681,9 @@ ARMTargetLowering::LowerCall(TargetLowering::CallLoweringInfo &CLI,
     } else if (ExternalSymbolSDNode *S=dyn_cast<ExternalSymbolSDNode>(Callee)) {
       const char *Sym = S->getSymbol();
 
-      // When generating execute-only code we use movw movt pair.
-      // Currently execute-only is only available for architectures that
-      // support movw movt, so we are safe to assume that.
       if (Subtarget->genExecuteOnly()) {
-        assert(Subtarget->useMovt() &&
-               "long-calls with execute-only requires movt and movw!");
-        ++NumMovwMovt;
+        if (Subtarget->useMovt())
+          ++NumMovwMovt;
         Callee = DAG.getNode(ARMISD::Wrapper, dl, PtrVt,
                              DAG.getTargetGlobalAddress(GVal, dl, PtrVt));
       } else {

diff  --git a/llvm/test/CodeGen/ARM/large-stack.ll b/llvm/test/CodeGen/ARM/large-stack.ll
index 52a006bd5a116..aedd8aa911fe2 100644
--- a/llvm/test/CodeGen/ARM/large-stack.ll
+++ b/llvm/test/CodeGen/ARM/large-stack.ll
@@ -1,4 +1,5 @@
 ; RUN: llc -mtriple=arm-eabi %s -o /dev/null
+; RUN: llc -mtriple=thumbv6m-eabi -mattr=+execute-only %s -o -
 
 define void @test1() {
     %tmp = alloca [ 64 x i32 ] , align 4

diff  --git a/llvm/test/CodeGen/Thumb/thumb-execute-only-long-calls.ll b/llvm/test/CodeGen/Thumb/thumb-execute-only-long-calls.ll
new file mode 100644
index 0000000000000..06735e16b56fa
--- /dev/null
+++ b/llvm/test/CodeGen/Thumb/thumb-execute-only-long-calls.ll
@@ -0,0 +1,34 @@
+; RUN: llc < %s -mtriple=thumbv6m-arm-none-eabi -relocation-model=static | FileCheck %s -check-prefixes=CHECK
+
+define void @fn() #0 {
+entry:
+; CHECK-LABEL: fn:
+; CHECK:       ldr [[REG:r[0-9]+]], .LCPI0_0
+; CHECK-NEXT:  blx [[REG]]
+; CHECK:       .LCPI0_0:
+; CHECK-NEXT:  .long   bar
+  call void @bar()
+  ret void
+}
+
+define void @execute_only_fn() #1 {
+; CHECK-LABEL: execute_only_fn:
+; CHECK:       movs    [[REG0:r[0-9]+]], :upper8_15:bar
+; CHECK-NEXT:  lsls    [[REG0]], r0, #8
+; CHECK-NEXT:  adds    [[REG0]], :upper0_7:bar
+; CHECK-NEXT:  lsls    [[REG0]], r0, #8
+; CHECK-NEXT:  adds    [[REG0]], :lower8_15:bar
+; CHECK-NEXT:  lsls    [[REG0]], r0, #8
+; CHECK-NEXT:  adds    [[REG0]], :lower0_7:bar
+; CHECK-NEXT:  blx     [[REG0]]
+; CHECK-NOT:   .LCPI1_0:
+
+entry:
+  call void @bar()
+  ret void
+}
+
+attributes #0 = { noinline optnone "target-features"="+thumb-mode,+long-calls" }
+attributes #1 = { noinline optnone "target-features"="+execute-only,+thumb-mode,+long-calls" }
+
+declare dso_local void @bar()

diff  --git a/llvm/test/CodeGen/Thumb2/thumb2-execute-only-long-calls.ll b/llvm/test/CodeGen/Thumb2/thumb2-execute-only-long-calls.ll
index 8a70dc2cf273c..79a6f06c6eb78 100644
--- a/llvm/test/CodeGen/Thumb2/thumb2-execute-only-long-calls.ll
+++ b/llvm/test/CodeGen/Thumb2/thumb2-execute-only-long-calls.ll
@@ -23,7 +23,7 @@ define void @execute_only_fn() #1 {
 ; RWPI:       movw    [[REG0:r[0-9]+]], :lower16:bar
 ; RWPI-NEXT:  movt    [[REG0]], :upper16:bar
 ; RWPI-NEXT:  blx     [[REG0]]
-; RWPI-NOT:   .LCPI0_0:
+; RWPI-NOT:   .LCPI1_0:
 entry:
   call void @bar()
   ret void