instead of 80-bits of precision. This fixes PR467.
This change speeds up fldry on X86 with LLC from 7.32s on apoc to 4.68s.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@18433 91177308-0d34-0410-b5e6-96231b3b80d8
to Brian and the Sun compiler for pointing out that the obvious works :)
This also enables folding all long comparisons into setcc and branch
instructions: before we could only do == and !=
For example, for:
void test(unsigned long long A, unsigned long long B) {
if (A < B) foo();
}
We now generate:
test:
subl $4, %esp
movl %esi, (%esp)
movl 8(%esp), %eax
movl 12(%esp), %ecx
movl 16(%esp), %edx
movl 20(%esp), %esi
subl %edx, %eax
sbbl %esi, %ecx
jae .LBBtest_2 # UnifiedReturnBlock
.LBBtest_1: # then
call foo
movl (%esp), %esi
addl $4, %esp
ret
.LBBtest_2: # UnifiedReturnBlock
movl (%esp), %esi
addl $4, %esp
ret
Instead of:
test:
subl $12, %esp
movl %esi, 8(%esp)
movl %ebx, 4(%esp)
movl 16(%esp), %eax
movl 20(%esp), %ecx
movl 24(%esp), %edx
movl 28(%esp), %esi
cmpl %edx, %eax
setb %al
cmpl %esi, %ecx
setb %bl
cmove %ax, %bx
testb %bl, %bl
je .LBBtest_2 # UnifiedReturnBlock
.LBBtest_1: # then
call foo
movl 4(%esp), %ebx
movl 8(%esp), %esi
addl $12, %esp
ret
.LBBtest_2: # UnifiedReturnBlock
movl 4(%esp), %ebx
movl 8(%esp), %esi
addl $12, %esp
ret
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@18330 91177308-0d34-0410-b5e6-96231b3b80d8
* Get rid of "emitMaybePCRelativeValue", either we want to emit a PC relative
value or not: drop the maybe BS. As it turns out, the only places where
the bool was a variable coming in, the bool was a dynamic constant.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@17867 91177308-0d34-0410-b5e6-96231b3b80d8
two or three, open code the equivalent operation which is faster on athlon
and P4 (by a substantial margin).
For example, instead of compiling this:
long long X2(long long Y) { return Y << 2; }
to:
X3_2:
movl 4(%esp), %eax
movl 8(%esp), %edx
shldl $2, %eax, %edx
shll $2, %eax
ret
Compile it to:
X2:
movl 4(%esp), %eax
movl 8(%esp), %ecx
movl %eax, %edx
shrl $30, %edx
leal (%edx,%ecx,4), %edx
shll $2, %eax
ret
Likewise, for << 3, compile to:
X3:
movl 4(%esp), %eax
movl 8(%esp), %ecx
movl %eax, %edx
shrl $29, %edx
leal (%edx,%ecx,8), %edx
shll $3, %eax
ret
This matches icc, except that icc open codes the shifts as adds on the P4.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@17707 91177308-0d34-0410-b5e6-96231b3b80d8
double %test(uint %X) {
%tmp.1 = cast uint %X to double ; <double> [#uses=1]
ret double %tmp.1
}
into:
test:
sub %ESP, 8
mov %EAX, DWORD PTR [%ESP + 12]
mov %ECX, 0
mov DWORD PTR [%ESP], %EAX
mov DWORD PTR [%ESP + 4], %ECX
fild QWORD PTR [%ESP]
add %ESP, 8
ret
... which basically zero extends to 8 bytes, then does an fild for an
8-byte signed int.
Now we generate this:
test:
sub %ESP, 4
mov %EAX, DWORD PTR [%ESP + 8]
mov DWORD PTR [%ESP], %EAX
fild DWORD PTR [%ESP]
shr %EAX, 31
fadd DWORD PTR [.CPItest_0 + 4*%EAX]
add %ESP, 4
ret
.section .rodata
.align 4
.CPItest_0:
.quad 5728578726015270912
This does a 32-bit signed integer load, then adds in an offset if the sign
bit of the integer was set.
It turns out that this is substantially faster than the preceeding sequence.
Consider this testcase:
unsigned a[2]={1,2};
volatile double G;
void main() {
int i;
for (i=0; i<100000000; ++i )
G += a[i&1];
}
On zion (a P4 Xeon, 3Ghz), this patch speeds up the testcase from 2.140s
to 0.94s.
On apoc, an athlon MP 2100+, this patch speeds up the testcase from 1.72s
to 1.34s.
Note that the program takes 2.5s/1.97s on zion/apoc with GCC 3.3 -O3
-fomit-frame-pointer.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@17083 91177308-0d34-0410-b5e6-96231b3b80d8
%X = and Y, constantint
%Z = setcc %X, 0
instead of emitting:
and %EAX, 3
test %EAX, %EAX
je .LBBfoo2_2 # UnifiedReturnBlock
We now emit:
test %EAX, 3
je .LBBfoo2_2 # UnifiedReturnBlock
This triggers 581 times on 176.gcc for example.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@17080 91177308-0d34-0410-b5e6-96231b3b80d8
case:
int C[100];
int foo() {
return C[4];
}
We now codegen:
foo:
mov %EAX, DWORD PTR [C + 16]
ret
instead of:
foo:
mov %EAX, OFFSET C
mov %EAX, DWORD PTR [%EAX + 16]
ret
Other impressive features may be coming later.
This patch is contributed by Jeff Cohen!
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@17011 91177308-0d34-0410-b5e6-96231b3b80d8
the -sse* options (to avoid misleading people).
Also, the stack alignment of the target doesn't depend on whether SSE is
eventually implemented, so remove a comment.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@16860 91177308-0d34-0410-b5e6-96231b3b80d8
which prevented setcc's from being folded into branches. It appears that
conditional branchinst's CC operand is actually operand(2), not operand(0)
as we might expect. :(
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@16859 91177308-0d34-0410-b5e6-96231b3b80d8
