From 5b2a07138fe11cb30c1492b8857c4749f7bf180a Mon Sep 17 00:00:00 2001
From: Dhruv Chopra <Dhruv.C.Chopra@ibm.com>
Date: Thu, 18 Jul 2024 21:03:55 -0400
Subject: [PATCH] Cap R0's value to 3 when handling complex structs in
 sysvz64.s

R0's value is used to calculate a branch offset. This value can be
between 0 and 3. Due to the nature of how complex types are passed in
registers, it's possible to increment this value beyond 3. This commit adds
some support code to cap that value at 3 before any branch offsets are computed.
---
 runtime/libffi/z/sysvz64.s | 21 +++++++++++++--------
 1 file changed, 13 insertions(+), 8 deletions(-)

diff --git a/runtime/libffi/z/sysvz64.s b/runtime/libffi/z/sysvz64.s
index 2d3ef29bc61..316b856f9e0 100644
--- a/runtime/libffi/z/sysvz64.s
+++ b/runtime/libffi/z/sysvz64.s
@@ -504,7 +504,7 @@ STFPCHKF26 DS 0H
          AFI 15,-4              we've handled 4 bytes
          AFI 7,4                advance 4 bytes into argarea
 
-         B STRCTLP              copy rest of struct
+         B CPXMRG               copy rest of struct
 
 STFPCHKF202 DS 0H
          LE 0,0(6,13)           first float
@@ -516,7 +516,7 @@ STFPCHKF202 DS 0H
          AFI 15,-8              we've handled 8 bytes (all the struct)
          AFI 7,8                bump local storage by 8 bytes
 
-         B STRCTLP
+         B CPXMRG
 
 STFPCHKF224 DS 0H
          LE 2,0(6,13)           first float
@@ -528,7 +528,7 @@ STFPCHKF224 DS 0H
          AFI 15,-8              we've handled 8 bytes (all the struct)
          AFI 7,8                bump local storage by 8 bytes
 
-         B STRCTLP
+         B CPXMRG
 
 
 STFPCHKF246 DS 0H
@@ -541,7 +541,7 @@ STFPCHKF246 DS 0H
          AFI 15,-8              we've handled 8 bytes (all the struct)
          AFI 7,8                bump local storage by 8 bytes
 
-         B STRCTLP
+         B CPXMRG
 
 CPXD     DS 0H
          CFI 14,4               no FPRs are available
@@ -571,7 +571,7 @@ STFPCHKD26 DS 0H
          AFI 15,-8
          AFI 7,8
 
-         B STRCTLP
+         B CPXMRG
 
 STFPCHKD202 DS 0H
          LD 0,0(6,13)           first double
@@ -583,7 +583,7 @@ STFPCHKD202 DS 0H
          AFI 15,-16
          AFI 7,16
 
-         B STRCTLP
+         B CPXMRG
 
 STFPCHKD224 DS 0H
          LD 2,0(6,13)           first double
@@ -595,7 +595,7 @@ STFPCHKD224 DS 0H
          AFI 15,-16
          AFI 7,16
 
-         B STRCTLP
+         B CPXMRG
 
 
 STFPCHKD246 DS 0H
@@ -608,7 +608,7 @@ STFPCHKD246 DS 0H
          AFI 15,-16
          AFI 7,16
 
-         B STRCTLP
+         B CPXMRG
 
 
 *determine how to pass the struct based on size
@@ -728,6 +728,11 @@ BYTE24R3 DS 0H               Struct goes in R3 and Memory
          LA 0,3
          B STRCTLP
 
+CPXMRG   DS 0H               Reached max GPRs, set R0 to 3
+         CFI 0,4
+         BL STRCTLP
+         LA 0,3
+
 STRCTLP  DS 0H               Rest of struct goes in Memory
          CFI 15,0            Size remaining > 0?
          BNH CONT