diff options
| -rw-r--r-- | lib/Target/Mips/MipsConstantIslandPass.cpp | 30 |
1 files changed, 6 insertions, 24 deletions
diff --git a/lib/Target/Mips/MipsConstantIslandPass.cpp b/lib/Target/Mips/MipsConstantIslandPass.cpp index 1c1652f..b15ec06 100644 --- a/lib/Target/Mips/MipsConstantIslandPass.cpp +++ b/lib/Target/Mips/MipsConstantIslandPass.cpp @@ -9,9 +9,7 @@ // // // This pass is used to make Pc relative loads of constants. -// For now, only Mips16 will use this. While it has the same name and -// uses many ideas from the LLVM ARM Constant Island Pass, it's not intended -// to reuse any of the code from the ARM version. +// For now, only Mips16 will use this. // // Loading constants inline is expensive on Mips16 and it's in general better // to place the constant nearby in code space and then it can be loaded with a @@ -783,10 +781,6 @@ unsigned MipsConstantIslands::getUserOffset(CPUser &U) const { // Make sure U.getMaxDisp() returns a constrained range. U.KnownAlignment = (KnownBits >= 2); - // On Thumb, offsets==2 mod 4 are rounded down by the hardware for - // purposes of the displacement computation; compensate for that here. - // For unknown alignments, getMaxDisp() constrains the range instead. - return UserOffset; } @@ -1115,8 +1109,8 @@ static inline unsigned getUnconditionalBrDisp(int Opc) { /// findAvailableWater - Look for an existing entry in the WaterList in which /// we can place the CPE referenced from U so it's within range of U's MI. /// Returns true if found, false if not. If it returns true, WaterIter -/// is set to the WaterList entry. For Thumb, prefer water that will not -/// introduce padding to water that will. To ensure that this pass +/// is set to the WaterList entry. +/// To ensure that this pass /// terminates, the CPE location for a particular CPUser is only allowed to /// move to a lower address, so search backward from the end of the list and /// prefer the first water that is in range. @@ -1175,9 +1169,7 @@ void MipsConstantIslands::createNewWater(unsigned CPUserIndex, const BasicBlockInfo &UserBBI = BBInfo[UserMBB->getNumber()]; // If the block does not end in an unconditional branch already, and if the - // end of the block is within range, make new water there. (The addition - // below is for the unconditional branch we will be adding: 4 bytes on ARM + - // Thumb2, 2 on Thumb1. + // end of the block is within range, make new water there. if (BBHasFallthrough(UserMBB)) { // Size of branch to insert. unsigned Delta = 2; @@ -1204,17 +1196,7 @@ void MipsConstantIslands::createNewWater(unsigned CPUserIndex, } } - // What a big block. Find a place within the block to split it. This is a - // little tricky on Thumb1 since instructions are 2 bytes and constant pool - // entries are 4 bytes: if instruction I references island CPE, and - // instruction I+1 references CPE', it will not work well to put CPE as far - // forward as possible, since then CPE' cannot immediately follow it (that - // location is 2 bytes farther away from I+1 than CPE was from I) and we'd - // need to create a new island. So, we make a first guess, then walk through - // the instructions between the one currently being looked at and the - // possible insertion point, and make sure any other instructions that - // reference CPEs will be able to use the same island area; if not, we back - // up the insertion point. + // What a big block. Find a place within the block to split it. // Try to split the block so it's fully aligned. Compute the latest split // point where we can add a 4-byte branch instruction, and then align to @@ -1228,7 +1210,7 @@ void MipsConstantIslands::createNewWater(unsigned CPUserIndex, BaseInsertOffset)); // The 4 in the following is for the unconditional branch we'll be inserting - // (allows for long branch on Thumb1). Alignment of the island is handled + // Alignment of the island is handled // inside isOffsetInRange. BaseInsertOffset -= 4; |