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| author | Karl Meakin <karl.meakin@arm.com> | 2025-07-03 12:48:29 +0100 |
|---|---|---|
| committer | Richard Sandiford <richard.sandiford@arm.com> | 2025-07-03 12:48:29 +0100 |
| commit | 70905bad8ea7e9e5f807b54ad3fe183f643cdbf2 (patch) | |
| tree | 1a8a7a54c4e4c99e7d93f793d10d9686d608cae0 | |
| parent | 2cc9b03a84601b7951e5e0a24f5174387f564f27 (diff) | |
| download | gcc-70905bad8ea7e9e5f807b54ad3fe183f643cdbf2.zip gcc-70905bad8ea7e9e5f807b54ad3fe183f643cdbf2.tar.gz gcc-70905bad8ea7e9e5f807b54ad3fe183f643cdbf2.tar.bz2 | |
AArch64: add constants for branch displacements
Extract the hardcoded values for the minimum PC-relative displacements
into named constants and document them.
gcc/ChangeLog:
* config/aarch64/aarch64.md (BRANCH_LEN_P_1MiB): New constant.
(BRANCH_LEN_N_1MiB): Likewise.
(BRANCH_LEN_P_32KiB): Likewise.
(BRANCH_LEN_N_32KiB): Likewise.
| -rw-r--r-- | gcc/config/aarch64/aarch64.md | 60 |
1 files changed, 44 insertions, 16 deletions
diff --git a/gcc/config/aarch64/aarch64.md b/gcc/config/aarch64/aarch64.md index 8ce991e..3f37ea6 100644 --- a/gcc/config/aarch64/aarch64.md +++ b/gcc/config/aarch64/aarch64.md @@ -704,7 +704,19 @@ [(set_attr "type" "branch")] ) +;; Maximum PC-relative positive/negative displacements for various branching +;; instructions. +(define_constants + [ + ;; +/- 1MiB. Used by B.<cond>, CBZ, CBNZ. + (BRANCH_LEN_P_1MiB 1048572) + (BRANCH_LEN_N_1MiB -1048576) + ;; +/- 32KiB. Used by TBZ, TBNZ. + (BRANCH_LEN_P_32KiB 32764) + (BRANCH_LEN_N_32KiB -32768) + ] +) ;; ------------------------------------------------------------------- ;; Conditional jumps @@ -769,13 +781,17 @@ } [(set_attr "type" "branch") (set (attr "length") - (if_then_else (and (ge (minus (match_dup 2) (pc)) (const_int -1048576)) - (lt (minus (match_dup 2) (pc)) (const_int 1048572))) + (if_then_else (and (ge (minus (match_dup 2) (pc)) + (const_int BRANCH_LEN_N_1MiB)) + (lt (minus (match_dup 2) (pc)) + (const_int BRANCH_LEN_P_1MiB))) (const_int 4) (const_int 8))) (set (attr "far_branch") - (if_then_else (and (ge (minus (match_dup 2) (pc)) (const_int -1048576)) - (lt (minus (match_dup 2) (pc)) (const_int 1048572))) + (if_then_else (and (ge (minus (match_dup 2) (pc)) + (const_int BRANCH_LEN_N_1MiB)) + (lt (minus (match_dup 2) (pc)) + (const_int BRANCH_LEN_P_1MiB))) (const_int 0) (const_int 1)))] ) @@ -830,13 +846,17 @@ } [(set_attr "type" "branch") (set (attr "length") - (if_then_else (and (ge (minus (match_dup 1) (pc)) (const_int -1048576)) - (lt (minus (match_dup 1) (pc)) (const_int 1048572))) + (if_then_else (and (ge (minus (match_dup 1) (pc)) + (const_int BRANCH_LEN_N_1MiB)) + (lt (minus (match_dup 1) (pc)) + (const_int BRANCH_LEN_P_1MiB))) (const_int 4) (const_int 8))) (set (attr "far_branch") - (if_then_else (and (ge (minus (match_dup 2) (pc)) (const_int -1048576)) - (lt (minus (match_dup 2) (pc)) (const_int 1048572))) + (if_then_else (and (ge (minus (match_dup 2) (pc)) + (const_int BRANCH_LEN_N_1MiB)) + (lt (minus (match_dup 2) (pc)) + (const_int BRANCH_LEN_P_1MiB))) (const_int 0) (const_int 1)))] ) @@ -870,13 +890,17 @@ } [(set_attr "type" "branch") (set (attr "length") - (if_then_else (and (ge (minus (match_dup 1) (pc)) (const_int -32768)) - (lt (minus (match_dup 1) (pc)) (const_int 32764))) + (if_then_else (and (ge (minus (match_dup 1) (pc)) + (const_int BRANCH_LEN_N_32KiB)) + (lt (minus (match_dup 1) (pc)) + (const_int BRANCH_LEN_P_32KiB))) (const_int 4) (const_int 8))) (set (attr "far_branch") - (if_then_else (and (ge (minus (match_dup 1) (pc)) (const_int -1048576)) - (lt (minus (match_dup 1) (pc)) (const_int 1048572))) + (if_then_else (and (ge (minus (match_dup 1) (pc)) + (const_int BRANCH_LEN_N_1MiB)) + (lt (minus (match_dup 1) (pc)) + (const_int BRANCH_LEN_P_1MiB))) (const_int 0) (const_int 1)))] ) @@ -931,13 +955,17 @@ } [(set_attr "type" "branch") (set (attr "length") - (if_then_else (and (ge (minus (match_dup 2) (pc)) (const_int -32768)) - (lt (minus (match_dup 2) (pc)) (const_int 32764))) + (if_then_else (and (ge (minus (match_dup 2) (pc)) + (const_int BRANCH_LEN_N_32KiB)) + (lt (minus (match_dup 2) (pc)) + (const_int BRANCH_LEN_P_32KiB))) (const_int 4) (const_int 8))) (set (attr "far_branch") - (if_then_else (and (ge (minus (match_dup 2) (pc)) (const_int -1048576)) - (lt (minus (match_dup 2) (pc)) (const_int 1048572))) + (if_then_else (and (ge (minus (match_dup 2) (pc)) + (const_int BRANCH_LEN_N_1MiB)) + (lt (minus (match_dup 2) (pc)) + (const_int BRANCH_LEN_P_1MiB))) (const_int 0) (const_int 1)))] |