exceptions to abort() in cases where it should not.
Many thanks to Duraid Madina for doing the heavy lifting on the analysis
of this problem.
llvm-svn: 19256
1. Add new instructions for checking parity flags: JP, JNP, SETP, SETNP.
2. Set the isCommutable and isPromotableTo3Address bits on several
instructions.
llvm-svn: 19246
1. If we are two-addressing a commutable instruction and the LHS is not the
last use of the variable, see if the instruction is the last use of the
RHS. If so, commute the instruction, allowing us to avoid a
register-register copy in many cases for common instructions like ADD, OR,
AND, etc on X86.
2. If #1 doesn't hold, and if this is an instruction that also existing in
3-address form, promote the instruction to a 3-address instruction to
avoid the register-register copy. We can do this for several common
instructions in X86, including ADDrr, INC, DEC, etc.
This patch implements test/Regression/CodeGen/X86/commute-two-addr.ll,
overlap-add.ll, and overlap-shift.ll when I check in the X86 support for it.
llvm-svn: 19245
* We can now fold cast instructions into select instructions that
have at least one constant operand.
* We now optimize expressions more aggressively based on bits that are
known to be zero. These optimizations occur a lot in code that uses
bitfields even in simple ways.
* We now turn more cast-cast sequences into AND instructions. Before we
would only do this if it if all types were unsigned. Now only the
middle type needs to be unsigned (guaranteeing a zero extend).
* We transform sign extensions into zero extensions in several cases.
This corresponds to these test/Regression/Transforms/InstCombine testcases:
2004-11-22-Missed-and-fold.ll
and.ll: test28-29
cast.ll: test21-24
and-or-and.ll
cast-cast-to-and.ll
zeroext-and-reduce.ll
llvm-svn: 19220
While we're at it, improve codegen of select instructions. For this
testcase:
int %test(bool %C, int %A, int %B) {
%D = select bool %C, int %A, int %B
ret int %D
}
We used to generate this code:
_test:
cmpwi cr0, r3, 0
bne .LBB_test_2 ;
.LBB_test_1: ;
b .LBB_test_3 ;
.LBB_test_2: ;
or r5, r4, r4
.LBB_test_3: ;
or r3, r5, r5
blr
Now we emit:
_test:
cmpwi cr0, r3, 0
bne .LBB_test_2 ;
.LBB_test_1: ;
or r4, r5, r5
.LBB_test_2: ;
or r3, r4, r4
blr
-Chris
llvm-svn: 19214
SimplifyCFG is one of those passes that we use for final cleanup: it should
not rely on other passes to clean up its garbage. This fixes the "why are
trivially dead setcc's in the output of gccas" problem.
llvm-svn: 19212