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authorJerome Guitton <guitton@adacore.com>2010-04-23 15:14:22 +0000
committerJerome Guitton <guitton@adacore.com>2010-04-23 15:14:22 +0000
commit3a48e6ff66b76a9bd077a7a3671f13b537e418cd (patch)
treeb76abf9e78350c0df5fb1677e0740cee5c5ddffa /gdb/alpha-tdep.c
parente4166a49ea402e8ec97329268d80cf75144c4628 (diff)
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* alpha-tdep.c (INSN_OPCODE, MEM_RA, MEM_RB, MEM_DISP, BR_RA)
(OPR_FUNCTION, OPR_HAS_IMMEDIATE, OPR_RA, OPR_RC, OPR_LIT): New macros. (lda_opcode, stq_opcode, bne_opcode, subq_opcode, subq_function): New constants. (alpha_heuristic_analyze_probing_loop): New function. (alpha_heuristic_frame_unwind_cache): In the prologue analysis, detect and handle cases when a stack probe loop is generated. * alpha-mdebug-tdep.c (alpha_mdebug_frameless): New function. (alpha_mdebug_max_frame_size_exceeded): New function. (alpha_mdebug_after_prologue): Use alpha_mdebug_frameless. (alpha_mdebug_frame_sniffer, alpha_mdebug_frame_base_sniffer): Return 0 when the maximum debuggable frame size has been exceeded.
Diffstat (limited to 'gdb/alpha-tdep.c')
-rw-r--r--gdb/alpha-tdep.c134
1 files changed, 134 insertions, 0 deletions
diff --git a/gdb/alpha-tdep.c b/gdb/alpha-tdep.c
index 2f583e9..8c93777 100644
--- a/gdb/alpha-tdep.c
+++ b/gdb/alpha-tdep.c
@@ -46,6 +46,36 @@
#include "alpha-tdep.h"
+/* Instruction decoding. The notations for registers, immediates and
+ opcodes are the same as the one used in Compaq's Alpha architecture
+ handbook. */
+
+#define INSN_OPCODE(insn) ((insn & 0xfc000000) >> 26)
+
+/* Memory instruction format */
+#define MEM_RA(insn) ((insn & 0x03e00000) >> 21)
+#define MEM_RB(insn) ((insn & 0x001f0000) >> 16)
+#define MEM_DISP(insn) \
+ (((insn & 0x8000) == 0) ? (insn & 0xffff) : -((-insn) & 0xffff))
+
+static const int lda_opcode = 0x08;
+static const int stq_opcode = 0x2d;
+
+/* Branch instruction format */
+#define BR_RA(insn) MEM_RA(insn)
+
+static const int bne_opcode = 0x3d;
+
+/* Operate instruction format */
+#define OPR_FUNCTION(insn) ((insn & 0xfe0) >> 5)
+#define OPR_HAS_IMMEDIATE(insn) ((insn & 0x1000) == 0x1000)
+#define OPR_RA(insn) MEM_RA(insn)
+#define OPR_RC(insn) ((insn & 0x1f))
+#define OPR_LIT(insn) ((insn & 0x1fe000) >> 13)
+
+static const int subq_opcode = 0x10;
+static const int subq_function = 0x29;
+
/* Return the name of the REGNO register.
@@ -1000,6 +1030,108 @@ struct alpha_heuristic_unwind_cache
int return_reg;
};
+/* If a probing loop sequence starts at PC, simulate it and compute
+ FRAME_SIZE and PC after its execution. Otherwise, return with PC and
+ FRAME_SIZE unchanged. */
+
+static void
+alpha_heuristic_analyze_probing_loop (struct gdbarch *gdbarch, CORE_ADDR *pc,
+ int *frame_size)
+{
+ CORE_ADDR cur_pc = *pc;
+ int cur_frame_size = *frame_size;
+ int nb_of_iterations, reg_index, reg_probe;
+ unsigned int insn;
+
+ /* The following pattern is recognized as a probing loop:
+
+ lda REG_INDEX,NB_OF_ITERATIONS
+ lda REG_PROBE,<immediate>(sp)
+
+ LOOP_START:
+ stq zero,<immediate>(REG_PROBE)
+ subq REG_INDEX,0x1,REG_INDEX
+ lda REG_PROBE,<immediate>(REG_PROBE)
+ bne REG_INDEX, LOOP_START
+
+ lda sp,<immediate>(REG_PROBE)
+
+ If anything different is found, the function returns without
+ changing PC and FRAME_SIZE. Otherwise, PC will point immediately
+ after this sequence, and FRAME_SIZE will be updated.
+ */
+
+ /* lda REG_INDEX,NB_OF_ITERATIONS */
+
+ insn = alpha_read_insn (gdbarch, cur_pc);
+ if (INSN_OPCODE (insn) != lda_opcode)
+ return;
+ reg_index = MEM_RA (insn);
+ nb_of_iterations = MEM_DISP (insn);
+
+ /* lda REG_PROBE,<immediate>(sp) */
+
+ cur_pc += ALPHA_INSN_SIZE;
+ insn = alpha_read_insn (gdbarch, cur_pc);
+ if (INSN_OPCODE (insn) != lda_opcode
+ || MEM_RB (insn) != ALPHA_SP_REGNUM)
+ return;
+ reg_probe = MEM_RA (insn);
+ cur_frame_size -= MEM_DISP (insn);
+
+ /* stq zero,<immediate>(REG_PROBE) */
+
+ cur_pc += ALPHA_INSN_SIZE;
+ insn = alpha_read_insn (gdbarch, cur_pc);
+ if (INSN_OPCODE (insn) != stq_opcode
+ || MEM_RA (insn) != 0x1f
+ || MEM_RB (insn) != reg_probe)
+ return;
+
+ /* subq REG_INDEX,0x1,REG_INDEX */
+
+ cur_pc += ALPHA_INSN_SIZE;
+ insn = alpha_read_insn (gdbarch, cur_pc);
+ if (INSN_OPCODE (insn) != subq_opcode
+ || !OPR_HAS_IMMEDIATE (insn)
+ || OPR_FUNCTION (insn) != subq_function
+ || OPR_LIT(insn) != 1
+ || OPR_RA (insn) != reg_index
+ || OPR_RC (insn) != reg_index)
+ return;
+
+ /* lda REG_PROBE,<immediate>(REG_PROBE) */
+
+ cur_pc += ALPHA_INSN_SIZE;
+ insn = alpha_read_insn (gdbarch, cur_pc);
+ if (INSN_OPCODE (insn) != lda_opcode
+ || MEM_RA (insn) != reg_probe
+ || MEM_RB (insn) != reg_probe)
+ return;
+ cur_frame_size -= MEM_DISP (insn) * nb_of_iterations;
+
+ /* bne REG_INDEX, LOOP_START */
+
+ cur_pc += ALPHA_INSN_SIZE;
+ insn = alpha_read_insn (gdbarch, cur_pc);
+ if (INSN_OPCODE (insn) != bne_opcode
+ || MEM_RA (insn) != reg_index)
+ return;
+
+ /* lda sp,<immediate>(REG_PROBE) */
+
+ cur_pc += ALPHA_INSN_SIZE;
+ insn = alpha_read_insn (gdbarch, cur_pc);
+ if (INSN_OPCODE (insn) != lda_opcode
+ || MEM_RA (insn) != ALPHA_SP_REGNUM
+ || MEM_RB (insn) != reg_probe)
+ return;
+ cur_frame_size -= MEM_DISP (insn);
+
+ *pc = cur_pc;
+ *frame_size = cur_frame_size;
+}
+
static struct alpha_heuristic_unwind_cache *
alpha_heuristic_frame_unwind_cache (struct frame_info *this_frame,
void **this_prologue_cache,
@@ -1116,6 +1248,8 @@ alpha_heuristic_frame_unwind_cache (struct frame_info *this_frame,
frame_reg = ALPHA_GCC_FP_REGNUM;
else if (word == 0x47fe040f) /* bis zero,sp,fp */
frame_reg = ALPHA_GCC_FP_REGNUM;
+
+ alpha_heuristic_analyze_probing_loop (gdbarch, &cur_pc, &frame_size);
}
/* If we haven't found a valid return address register yet, keep