diff options
Diffstat (limited to 'lib/CodeGen/README.txt')
-rw-r--r-- | lib/CodeGen/README.txt | 38 |
1 files changed, 19 insertions, 19 deletions
diff --git a/lib/CodeGen/README.txt b/lib/CodeGen/README.txt index aa5a54c3ba..8e6b0a5e46 100644 --- a/lib/CodeGen/README.txt +++ b/lib/CodeGen/README.txt @@ -2,29 +2,29 @@ Common register allocation / spilling problem: - mul lr, r4, lr - str lr, [sp, #+52] - ldr lr, [r1, #+32] - sxth r3, r3 - ldr r4, [sp, #+52] - mla r4, r3, lr, r4 + mul lr, r4, lr + str lr, [sp, #+52] + ldr lr, [r1, #+32] + sxth r3, r3 + ldr r4, [sp, #+52] + mla r4, r3, lr, r4 can be: - mul lr, r4, lr + mul lr, r4, lr mov r4, lr - str lr, [sp, #+52] - ldr lr, [r1, #+32] - sxth r3, r3 - mla r4, r3, lr, r4 + str lr, [sp, #+52] + ldr lr, [r1, #+32] + sxth r3, r3 + mla r4, r3, lr, r4 and then "merge" mul and mov: - mul r4, r4, lr - str lr, [sp, #+52] - ldr lr, [r1, #+32] - sxth r3, r3 - mla r4, r3, lr, r4 + mul r4, r4, lr + str lr, [sp, #+52] + ldr lr, [r1, #+32] + sxth r3, r3 + mla r4, r3, lr, r4 It also increase the likelyhood the store may become dead. @@ -70,13 +70,13 @@ Some potential added complexities: bb27 ... ... - %reg1037 = ADDri %reg1039, 1 - %reg1038 = ADDrs %reg1032, %reg1039, %NOREG, 10 + %reg1037 = ADDri %reg1039, 1 + %reg1038 = ADDrs %reg1032, %reg1039, %NOREG, 10 Successors according to CFG: 0x8b03bf0 (#5) bb76 (0x8b03bf0, LLVM BB @0x8b032d0, ID#5): Predecessors according to CFG: 0x8b0c5f0 (#3) 0x8b0a7c0 (#4) - %reg1039 = PHI %reg1070, mbb<bb76.outer,0x8b0c5f0>, %reg1037, mbb<bb27,0x8b0a7c0> + %reg1039 = PHI %reg1070, mbb<bb76.outer,0x8b0c5f0>, %reg1037, mbb<bb27,0x8b0a7c0> Note ADDri is not a two-address instruction. However, its result %reg1037 is an operand of the PHI node in bb76 and its operand %reg1039 is the result of the |