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6824f127f9
System z branches have a mask to select which of the 4 CC values should cause the branch to be taken. We can invert a branch by inverting the mask. However, not all instructions can produce all 4 CC values, so inverting the branch like this can lead to some oddities. For example, integer comparisons only produce a CC of 0 (equal), 1 (less) or 2 (greater). If an integer EQ is reversed to NE before instruction selection, the branch will test for 1 or 2. If instead the branch is reversed after instruction selection (by inverting the mask), it will test for 1, 2 or 3. Both are correct, but the second isn't really canonical. This patch therefore keeps track of which CC values are possible and uses this when inverting a mask. Although this is mostly cosmestic, it fixes undefined behavior for the CIJNLH in branch-08.ll. Another fix would have been to mask out bit 0 when generating the fused compare and branch, but the point of this patch is that we shouldn't need to do that in the first place. The patch also makes it easier to reuse CC results from other instructions. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@187495 91177308-0d34-0410-b5e6-96231b3b80d8
49 lines
1.1 KiB
LLVM
49 lines
1.1 KiB
LLVM
; Test LOCR and LOCGR.
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;
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; RUN: llc < %s -mtriple=s390x-linux-gnu -mcpu=z196 | FileCheck %s
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; Test LOCR.
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define i32 @f1(i32 %a, i32 %b, i32 %limit) {
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; CHECK-LABEL: f1:
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; CHECK: clfi %r4, 42
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; CHECK: locrhe %r2, %r3
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; CHECK: br %r14
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%cond = icmp ult i32 %limit, 42
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%res = select i1 %cond, i32 %a, i32 %b
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ret i32 %res
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}
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; Test LOCGR.
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define i64 @f2(i64 %a, i64 %b, i64 %limit) {
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; CHECK-LABEL: f2:
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; CHECK: clgfi %r4, 42
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; CHECK: locgrhe %r2, %r3
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; CHECK: br %r14
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%cond = icmp ult i64 %limit, 42
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%res = select i1 %cond, i64 %a, i64 %b
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ret i64 %res
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}
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; Test LOCR in a case that could use COMPARE AND BRANCH. We prefer using
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; LOCR if possible.
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define i32 @f3(i32 %a, i32 %b, i32 %limit) {
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; CHECK-LABEL: f3:
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; CHECK: chi %r4, 42
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; CHECK: locrlh %r2, %r3
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; CHECK: br %r14
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%cond = icmp eq i32 %limit, 42
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%res = select i1 %cond, i32 %a, i32 %b
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ret i32 %res
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}
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; ...and again for LOCGR.
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define i64 @f4(i64 %a, i64 %b, i64 %limit) {
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; CHECK-LABEL: f4:
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; CHECK: cghi %r4, 42
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; CHECK: locgrlh %r2, %r3
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; CHECK: br %r14
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%cond = icmp eq i64 %limit, 42
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%res = select i1 %cond, i64 %a, i64 %b
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ret i64 %res
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}
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