[llvm] [ARM] setCallFrameSize in ABS lowering. (PR #147195)

[David Green via llvm-commits]

https://github.com/davemgreen created https://github.com/llvm/llvm-project/pull/147195

ABS needs apparently to generate multiple BBs in EmitInstrWithCustomInserter. The CallFrameSize needs to be copied to the new blocks created, to prevent the verifier from complaining.

>From 14476b8361acc2cd2d221156ffc6f8725faa315e Mon Sep 17 00:00:00 2001
From: David Green <david.green at arm.com>
Date: Sun, 6 Jul 2025 16:28:35 +0100
Subject: [PATCH] [ARM] setCallFrameSize in ABS lowering.

ABS needs apparently to generate multiple BBs in EmitInstrWithCustomInserter.
The CallFrameSize needs to be copied to prevent the verifier from complaining.
---
 llvm/lib/Target/ARM/ARMISelLowering.cpp |  5 +++
 llvm/test/CodeGen/Thumb2/abs.ll         | 50 +++++++++++++++++++++++++
 2 files changed, 55 insertions(+)

diff --git a/llvm/lib/Target/ARM/ARMISelLowering.cpp b/llvm/lib/Target/ARM/ARMISelLowering.cpp
index 2d73725291d11..b974533d5fa1d 100644
--- a/llvm/lib/Target/ARM/ARMISelLowering.cpp
+++ b/llvm/lib/Target/ARM/ARMISelLowering.cpp
@@ -12383,6 +12383,11 @@ ARMTargetLowering::EmitInstrWithCustomInserter(MachineInstr &MI,
     // fall through to SinkMBB
     RSBBB->addSuccessor(SinkBB);
 
+    // Set the call frame size on entry to the new basic blocks.
+    unsigned CallFrameSize = TII->getCallFrameSizeAt(MI);
+    RSBBB->setCallFrameSize(CallFrameSize);
+    SinkBB->setCallFrameSize(CallFrameSize);
+
     // insert a cmp at the end of BB
     BuildMI(BB, dl, TII->get(isThumb2 ? ARM::t2CMPri : ARM::CMPri))
         .addReg(ABSSrcReg)
diff --git a/llvm/test/CodeGen/Thumb2/abs.ll b/llvm/test/CodeGen/Thumb2/abs.ll
index 88259ba758803..13af5145748c8 100644
--- a/llvm/test/CodeGen/Thumb2/abs.ll
+++ b/llvm/test/CodeGen/Thumb2/abs.ll
@@ -205,3 +205,53 @@ define i128 @abs128(i128 %x) {
   ret i128 %abs
 }
 
+define dso_local void @pr147162(ptr %p, ptr %q) #0 {
+; CHECKT1-LABEL: pr147162:
+; CHECKT1:       @ %bb.0: @ %entry
+; CHECKT1-NEXT:    .save {r7, lr}
+; CHECKT1-NEXT:    push {r7, lr}
+; CHECKT1-NEXT:    .pad #8
+; CHECKT1-NEXT:    sub sp, #8
+; CHECKT1-NEXT:    mov r3, r0
+; CHECKT1-NEXT:    ldrb r0, [r0]
+; CHECKT1-NEXT:    ldrb r1, [r1]
+; CHECKT1-NEXT:    movs r2, #1
+; CHECKT1-NEXT:    str r2, [sp]
+; CHECKT1-NEXT:    subs r0, r0, r1
+; CHECKT1-NEXT:    asrs r1, r0, #31
+; CHECKT1-NEXT:    eors r0, r1
+; CHECKT1-NEXT:    subs r0, r0, r1
+; CHECKT1-NEXT:    movs r1, #2
+; CHECKT1-NEXT:    bl call
+; CHECKT1-NEXT:    add sp, #8
+; CHECKT1-NEXT:    pop {r7, pc}
+;
+; CHECKT2-LABEL: pr147162:
+; CHECKT2:       @ %bb.0: @ %entry
+; CHECKT2-NEXT:    .save {r7, lr}
+; CHECKT2-NEXT:    push {r7, lr}
+; CHECKT2-NEXT:    .pad #8
+; CHECKT2-NEXT:    sub sp, #8
+; CHECKT2-NEXT:    mov r3, r0
+; CHECKT2-NEXT:    ldrb r0, [r0]
+; CHECKT2-NEXT:    ldrb r1, [r1]
+; CHECKT2-NEXT:    movs r2, #1
+; CHECKT2-NEXT:    str r2, [sp]
+; CHECKT2-NEXT:    subs r0, r0, r1
+; CHECKT2-NEXT:    mov.w r1, #2
+; CHECKT2-NEXT:    it mi
+; CHECKT2-NEXT:    rsbmi r0, r0, #0
+; CHECKT2-NEXT:    bl call
+; CHECKT2-NEXT:    add sp, #8
+; CHECKT2-NEXT:    pop {r7, pc}
+entry:
+  %0 = load i8, ptr %p, align 1
+  %conv = zext i8 %0 to i32
+  %1 = load i8, ptr %q, align 1
+  %conv1 = zext i8 %1 to i32
+  %sub = sub nsw i32 %conv, %conv1
+  %2 = tail call i32 @llvm.abs.i32(i32 %sub, i1 true)
+  tail call void @call(i32 noundef %2, i32 noundef 2, i32 noundef 1, ptr noundef nonnull %p, i32 noundef 1)
+  ret void
+}
+declare void @call(i32, i32, i32, ptr, i32)