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llvm-project/llvm/test/Transforms/InstCombine/preserve-sminmax.ll

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Convert a few tests to FileCheck for PR5307. llvm-svn: 85171
2009-10-27 06:52:03 +08:00
; RUN: opt < %s -instcombine -S | FileCheck %s
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. llvm-svn: 56246
2008-09-17 02:46:06 +08:00
; 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
}
Convert a few tests to FileCheck for PR5307. llvm-svn: 85171
2009-10-27 06:52:03 +08:00
; CHECK: %sd = sdiv i32 %h, 2
; CHECK: %t = icmp slt i32 %sd, 1
; CHECK: %r = select i1 %t, i32 %sd, i32 1
; CHECK: ret i32 %r
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. llvm-svn: 56246
2008-09-17 02:46:06 +08:00
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
}
Convert a few tests to FileCheck for PR5307. llvm-svn: 85171
2009-10-27 06:52:03 +08:00
; CHECK: %sd = sdiv i32 %h, 2
; CHECK: %t = icmp sgt i32 %sd, 1
; CHECK: %r = select i1 %t, i32 %sd, i32 1
; CHECK: ret i32 %r