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llvm-mirror/test/CodeGen/X86/pre-ra-sched.ll
Andrew Trick e3e67d4a0a Enable MI Sched for x86.
This changes the SelectionDAG scheduling preference to source
order. Soon, the SelectionDAG scheduler can be bypassed saving
a nice chunk of compile time.

Performance differences that result from this change are often a
consequence of register coalescing. The register coalescer is far from
perfect. Bugs can be filed for deficiencies.

On x86 SandyBridge/Haswell, the source order schedule is often
preserved, particularly for small blocks.

Register pressure is generally improved over the SD scheduler's ILP
mode. However, we are still able to handle large blocks that require
latency hiding, unlike the SD scheduler's BURR mode. MI scheduler also
attempts to discover the critical path in single-block loops and
adjust heuristics accordingly.

The MI scheduler relies on the new machine model. This is currently
unimplemented for AVX, so we may not be generating the best code yet.

Unit tests are updated so they don't depend on SD scheduling heuristics.

llvm-svn: 192750
2013-10-15 23:33:07 +00:00

58 lines
1.6 KiB
LLVM

; RUN-disabled: llc < %s -mtriple=x86_64-apple-macosx -pre-RA-sched=ilp -debug-only=pre-RA-sched \
; RUN-disabled: 2>&1 | FileCheck %s
; RUN: true
; REQUIRES: asserts
;
; rdar:13279013: pre-RA-sched should not check all interferences and
; repush them on the ready queue after scheduling each instruction.
;
; CHECK: *** List Scheduling
; CHECK: Interfering reg EFLAGS
; CHECK: Repushing
; CHECK: Repushing
; CHECK: Repushing
; CHECK-NOT: Repushing
; CHECK: *** Final schedule
define i32 @test(i8* %pin) #0 {
%g0 = getelementptr inbounds i8* %pin, i64 0
%l0 = load i8* %g0, align 1
%g1a = getelementptr inbounds i8* %pin, i64 1
%l1a = load i8* %g1a, align 1
%z1a = zext i8 %l1a to i32
%g1b = getelementptr inbounds i8* %pin, i64 2
%l1b = load i8* %g1b, align 1
%z1b = zext i8 %l1b to i32
%c1 = icmp ne i8 %l0, 0
%x1 = xor i32 %z1a, %z1b
%s1 = select i1 %c1, i32 %z1a, i32 %x1
%g2a = getelementptr inbounds i8* %pin, i64 3
%l2a = load i8* %g2a, align 1
%z2a = zext i8 %l2a to i32
%g2b = getelementptr inbounds i8* %pin, i64 4
%l2b = load i8* %g2b, align 1
%z2b = zext i8 %l2b to i32
%x2 = xor i32 %z2a, %z2b
%s2 = select i1 %c1, i32 %z2a, i32 %x2
%g3a = getelementptr inbounds i8* %pin, i64 5
%l3a = load i8* %g3a, align 1
%z3a = zext i8 %l3a to i32
%g3b = getelementptr inbounds i8* %pin, i64 6
%l3b = load i8* %g3b, align 1
%z3b = zext i8 %l3b to i32
%x3 = xor i32 %z3a, %z3b
%s3 = select i1 %c1, i32 %z3a, i32 %x3
%c3 = icmp ne i8 %l1a, 0
%c4 = icmp ne i8 %l2a, 0
%s4 = select i1 %c3, i32 %s1, i32 %s2
%s5 = select i1 %c4, i32 %s4, i32 %s3
ret i32 %s5
}
attributes #0 = { nounwind ssp uwtable }