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| author | Dan Gohman <gohman@apple.com> | 2008-09-16 18:46:06 +0000 |
|---|---|---|
| committer | Dan Gohman <gohman@apple.com> | 2008-09-16 18:46:06 +0000 |
| commit | 58c0963876292d4233b924f8932ef7cf7124ed2a (patch) | |
| tree | 057a8a72e899e9640c6b3892016da39c468f4fa6 /test | |
| parent | d23312adabdc88dee2c6df450c489aa58c096bb7 (diff) | |
| download | external_llvm-58c0963876292d4233b924f8932ef7cf7124ed2a.zip external_llvm-58c0963876292d4233b924f8932ef7cf7124ed2a.tar.gz external_llvm-58c0963876292d4233b924f8932ef7cf7124ed2a.tar.bz2 | |
Improve instcombine's handling of integer min and max in two ways:
- Recognize expressions like "x > -1 ? x : 0" as min/max and turn them
into expressions like "x < 0 ? 0 : x", which is easily recognizable
as a min/max operation.
- Refrain from folding expression like "y/2 < 1" to "y < 2" when the
comparison is being used as part of a min or max idiom, like
"y/2 < 1 ? 1 : y/2". In that case, the division has another use, so
folding doesn't eliminate it, and obfuscates the min/max, making it
harder to recognize as a min/max operation.
These benefit ScalarEvolution, CodeGen, and anything else that wants to
recognize integer min and max.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@56246 91177308-0d34-0410-b5e6-96231b3b80d8
Diffstat (limited to 'test')
| -rw-r--r-- | test/Transforms/InstCombine/adjust-for-sminmax.ll | 85 | ||||
| -rw-r--r-- | test/Transforms/InstCombine/preserve-sminmax.ll | 22 |
2 files changed, 107 insertions, 0 deletions
diff --git a/test/Transforms/InstCombine/adjust-for-sminmax.ll b/test/Transforms/InstCombine/adjust-for-sminmax.ll new file mode 100644 index 0000000..9328ad3 --- /dev/null +++ b/test/Transforms/InstCombine/adjust-for-sminmax.ll @@ -0,0 +1,85 @@ +; RUN: llvm-as < %s | opt -instcombine | llvm-dis | grep {icmp s\[lg\]t i32 %n, 0} | count 16 + +; Instcombine should recognize that this code can be adjusted +; to fit the canonical smax/smin pattern. + +define i32 @floor_a(i32 %n) { + %t = icmp sgt i32 %n, -1 + %m = select i1 %t, i32 %n, i32 0 + ret i32 %m +} +define i32 @ceil_a(i32 %n) { + %t = icmp slt i32 %n, 1 + %m = select i1 %t, i32 %n, i32 0 + ret i32 %m +} +define i32 @floor_b(i32 %n) { + %t = icmp sgt i32 %n, 0 + %m = select i1 %t, i32 %n, i32 0 + ret i32 %m +} +define i32 @ceil_b(i32 %n) { + %t = icmp slt i32 %n, 0 + %m = select i1 %t, i32 %n, i32 0 + ret i32 %m +} +define i32 @floor_c(i32 %n) { + %t = icmp sge i32 %n, 0 + %m = select i1 %t, i32 %n, i32 0 + ret i32 %m +} +define i32 @ceil_c(i32 %n) { + %t = icmp sle i32 %n, 0 + %m = select i1 %t, i32 %n, i32 0 + ret i32 %m +} +define i32 @floor_d(i32 %n) { + %t = icmp sge i32 %n, 1 + %m = select i1 %t, i32 %n, i32 0 + ret i32 %m +} +define i32 @ceil_d(i32 %n) { + %t = icmp sle i32 %n, -1 + %m = select i1 %t, i32 %n, i32 0 + ret i32 %m +} +define i32 @floor_e(i32 %n) { + %t = icmp sgt i32 %n, -1 + %m = select i1 %t, i32 %n, i32 0 + ret i32 %m +} +define i32 @ceil_e(i32 %n) { + %t = icmp slt i32 %n, 1 + %m = select i1 %t, i32 %n, i32 0 + ret i32 %m +} +define i32 @floor_f(i32 %n) { + %t = icmp sgt i32 %n, 0 + %m = select i1 %t, i32 %n, i32 0 + ret i32 %m +} +define i32 @ceil_f(i32 %n) { + %t = icmp slt i32 %n, 0 + %m = select i1 %t, i32 %n, i32 0 + ret i32 %m +} +define i32 @floor_g(i32 %n) { + %t = icmp sge i32 %n, 0 + %m = select i1 %t, i32 %n, i32 0 + ret i32 %m +} +define i32 @ceil_g(i32 %n) { + %t = icmp sle i32 %n, 0 + %m = select i1 %t, i32 %n, i32 0 + ret i32 %m +} +define i32 @floor_h(i32 %n) { + %t = icmp sge i32 %n, 1 + %m = select i1 %t, i32 %n, i32 0 + ret i32 %m +} +define i32 @ceil_h(i32 %n) { + %t = icmp sle i32 %n, -1 + %m = select i1 %t, i32 %n, i32 0 + ret i32 %m +} diff --git a/test/Transforms/InstCombine/preserve-sminmax.ll b/test/Transforms/InstCombine/preserve-sminmax.ll new file mode 100644 index 0000000..24fb7da --- /dev/null +++ b/test/Transforms/InstCombine/preserve-sminmax.ll @@ -0,0 +1,22 @@ +; RUN: llvm-as < %s | opt -instcombine | llvm-dis | grep { i32 \[%\]sd, \[\[:alnum:\]\]* \\?1\\>} | count 4 + +; Instcombine normally would fold the sdiv into the comparison, +; making "icmp slt i32 %h, 2", but in this case the sdiv has +; another use, so it wouldn't a big win, and it would also +; obfuscate an otherise obvious smax pattern to the point where +; other analyses wouldn't recognize it. + +define i32 @foo(i32 %h) { + %sd = sdiv i32 %h, 2 + %t = icmp slt i32 %sd, 1 + %r = select i1 %t, i32 %sd, i32 1 + ret i32 %r +} + +define i32 @bar(i32 %h) { + %sd = sdiv i32 %h, 2 + %t = icmp sgt i32 %sd, 1 + %r = select i1 %t, i32 %sd, i32 1 + ret i32 %r +} + |