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Diffstat (limited to 'lib/Target/README.txt')
| -rw-r--r-- | lib/Target/README.txt | 48 |
1 files changed, 0 insertions, 48 deletions
diff --git a/lib/Target/README.txt b/lib/Target/README.txt index b3bc749856..c0a2b760de 100644 --- a/lib/Target/README.txt +++ b/lib/Target/README.txt @@ -2274,51 +2274,3 @@ llc time when it gets inlined, because we can use smaller transfers. This also avoids partial register stalls in some important cases. //===---------------------------------------------------------------------===// - -With PR8575 we're now generating better code for: - -static _Bool foo(int x) { return x == 1; } -static _Bool bar(int x) { return x == 2; } -static _Bool baz(int x) { return x == 3; } - -_Bool quux(int x) { - return foo(x) || bar(x) || baz(x); -} - -$ clang t.c -S -o - -O3 -mkernel -fomit-frame-pointer -_quux: ## @quux -## BB#0: ## %entry - decl %edi - cmpl $3, %edi - movb $1, %al - jb LBB0_2 -## BB#1: ## %lor.rhs - xorb %al, %al -LBB0_2: ## %lor.end - movzbl %al, %eax - andl $1, %eax - ret - -But this should use a "setcc" instead of materializing a 0/1 value -the hard way. This looks like #1: simplifycfg should transform the -switch into a sub+icmp+branch, and an instcombine hack to replace -the PHI with a zext of the branch condition. Here's the IR today: - -define zeroext i1 @quux(i32 %x) nounwind readnone ssp noredzone { -entry: - switch i32 %x, label %lor.rhs [ - i32 1, label %lor.end - i32 2, label %lor.end - i32 3, label %lor.end - ] - -lor.rhs: ; preds = %entry - br label %lor.end - -lor.end: ; preds = %lor.rhs, %entry, %entry, %entry - %0 = phi i1 [ true, %entry ], [ false, %lor.rhs ], [ true, %entry ], [ true, %entry ] - ret i1 %0 -} - -//===---------------------------------------------------------------------===// - |