[PATCH]: b8b6f3ec67 target/armv4_5.c: mark registers as 'save-restore'

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"Tomas Vanek <va...@fb...>" just uploaded a new patch set to Gerrit, which you can find at https://review.openocd.org/c/openocd/+/9208

-- gerrit

commit b8b6f3ec67c381fa094e31d5a59f2fd50aaca69d
Author: Tomas Vanek <va...@fb...>
Date:   Mon Nov 3 08:50:32 2025 +0100

    target/armv4_5.c: mark registers as 'save-restore'
    
    gdb uses this mark when creating a dummy frame for
    manual call of a function by gdb command.
    With the original setting all registers as caller_save = false
    call command in gdb always clobbers r0, r1 and pc
    and some other registers depending on the called function.
    
    Set 'save-restore' for registers which are not preserved
    across function call.
    
    Change-Id: I16c49e4bf8001e38d18ce8861ca65988b08ccc88
    Signed-off-by: Tomas Vanek <va...@fb...>

diff --git a/src/target/armv4_5.c b/src/target/armv4_5.c
index d1a81614e8..8a4d2a0a77 100644
--- a/src/target/armv4_5.c
+++ b/src/target/armv4_5.c
@@ -690,8 +690,6 @@ struct reg_cache *arm_build_reg_cache(struct target *target, struct arm *arm)
 			&& arm->core_type != ARM_CORE_TYPE_VIRT_EXT)
 			continue;
 
-		/* REVISIT handle Cortex-M, which only shadows R13/SP */
-
 		reg_arch_info[i].num = arm_core_regs[i].cookie;
 		reg_arch_info[i].mode = arm_core_regs[i].mode;
 		reg_arch_info[i].target = target;
@@ -705,8 +703,11 @@ struct reg_cache *arm_build_reg_cache(struct target *target, struct arm *arm)
 		reg_list[i].arch_info = &reg_arch_info[i];
 		reg_list[i].exist = true;
 
-		/* This really depends on the calling convention in use */
-		reg_list[i].caller_save = false;
+		/* This really depends on the calling convention in use.
+		 * Set to loosely reflect AAPCS and checked with gdb function
+		 * call command not to change the registers of the debugged program. */
+		reg_list[i].caller_save = i < 4 || i == 9
+								  || i == 15;  // PC
 
 		/* Registers data type, as used by GDB target description */
 		reg_list[i].reg_data_type = malloc(sizeof(struct reg_data_type));
@@ -750,7 +751,8 @@ struct reg_cache *arm_build_reg_cache(struct target *target, struct arm *arm)
 		reg_list[i].arch_info = &reg_arch_info[i];
 		reg_list[i].exist = true;
 
-		reg_list[i].caller_save = false;
+		/* Mark d0 - d7, d16 - d31 as save-restore for gdb */
+		reg_list[i].caller_save = j < 8 || (j >= 16 && j < 32);
 
 		reg_list[i].reg_data_type = malloc(sizeof(struct reg_data_type));
 		reg_list[i].reg_data_type->type = arm_vfp_v3_regs[j].type;

--