[llvm] 77981e3 - [ARM] Fix chkstk definition (#210940)

[via llvm-commits]

Author: Trung Nguyen
Date: 2026-07-22T07:56:51-07:00
New Revision: 77981e39b5fa26ab43a3a3611fbb247321e33d78

URL: https://github.com/llvm/llvm-project/commit/77981e39b5fa26ab43a3a3611fbb247321e33d78
DIFF: https://github.com/llvm/llvm-project/commit/77981e39b5fa26ab43a3a3611fbb247321e33d78.diff

LOG: [ARM] Fix chkstk definition (#210940)

Added: 
    llvm/test/CodeGen/ARM/Windows/chkstk-cpsr-clobber.ll

Modified: 
    llvm/lib/Target/ARM/ARMInstrInfo.td

Removed: 
    


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diff  --git a/llvm/lib/Target/ARM/ARMInstrInfo.td b/llvm/lib/Target/ARM/ARMInstrInfo.td
index 397342841a89b..4ba7a447e2edf 100644
--- a/llvm/lib/Target/ARM/ARMInstrInfo.td
+++ b/llvm/lib/Target/ARM/ARMInstrInfo.td
@@ -6041,7 +6041,7 @@ def MSRbanked : ABI<0b0001, (outs), (ins banked_reg:$banked, GPRnopc:$Rn),
 def win__chkstk : SDNode<"ARMISD::WIN__CHKSTK", SDTNone,
                       [SDNPHasChain, SDNPSideEffect]>;
 
-let usesCustomInserter = 1, Uses = [R4], Defs = [R4, SP], hasNoSchedulingInfo = 1 in
+let usesCustomInserter = 1, Uses = [R4], Defs = [R4, R12, LR, SP, CPSR], hasNoSchedulingInfo = 1 in
   def WIN__CHKSTK : PseudoInst<(outs), (ins), NoItinerary, [(win__chkstk)]>;
 
 // Windows' divide by zero check

diff  --git a/llvm/test/CodeGen/ARM/Windows/chkstk-cpsr-clobber.ll b/llvm/test/CodeGen/ARM/Windows/chkstk-cpsr-clobber.ll
new file mode 100644
index 0000000000000..b0be9df632557
--- /dev/null
+++ b/llvm/test/CodeGen/ARM/Windows/chkstk-cpsr-clobber.ll
@@ -0,0 +1,25 @@
+; RUN: llc -O2 -mtriple=thumbv7-windows %s -o - | FileCheck %s
+
+; Ensure that __chkstk correctly marks CPSR as clobbered so that conditional
+; operations after dynamic stack allocation re-evaluate condition flags.
+
+define arm_aapcs_vfpcc void @chkstk_cpsr_clobber(i32 %n) {
+entry:
+  %cmp = icmp sgt i32 %n, 0
+  %max = select i1 %cmp, i32 %n, i32 1
+  %vla = alloca i8, i32 %max
+  br i1 %cmp, label %then, label %exit
+
+then:
+  store volatile i8 1, ptr %vla
+  ret void
+
+exit:
+  ret void
+}
+
+; CHECK-LABEL: chkstk_cpsr_clobber:
+; CHECK:         bl __chkstk
+; CHECK:         sub.w sp, sp, r4
+; CHECK:         cmp r0, #0
+; CHECK:         it gt